Patent Publication Number: US-2013252264-A1

Title: Methods and compositions for the evaluation of renal injury using hyaluronic acid

Description:
The present application claims priority to U.S. Provisional Patent Application 61/386,421 filed Sep. 24, 2010, which is hereby incorporated in its entirety including all tables, figures, and claims. 
    
    
     STATEMENT OF GOVERNMENTAL SUPPORT 
     This invention was made with government support under Grant/Contract No. 5R01DK070910-035R01DK070910-03 awarded by the National Institutes of Diabetes and Digestive and Kidney Diseases. The government has certain rights in the invention. 
    
    
     BACKGROUND OF THE INVENTION 
     The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention. 
     The kidney is responsible for water and solute excretion from the body. Its functions include maintenance of acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure. As such, loss of kidney function through injury and/or disease results in substantial morbidity and mortality. A detailed discussion of renal injuries is provided in Harrison&#39;s Principles of Internal Medicine, 17 th  Ed., McGraw Hill, New York, pages 1741-1830, which are hereby incorporated by reference in their entirety. Renal disease and/or injury may be acute or chronic. Acute and chronic kidney disease are described as follows (from Current Medical Diagnosis &amp; Treatment 2008, 47 th  Ed, McGraw Hill, New York, pages 785-815, which are hereby incorporated by reference in their entirety): “Acute renal failure is worsening of renal function over hours to days, resulting in the retention of nitrogenous wastes (such as urea nitrogen) and creatinine in the blood. Retention of these substances is called azotemia. Chronic renal failure (chronic kidney disease) results from an abnormal loss of renal function over months to years”. 
     Acute renal failure (ARF, also known as acute kidney injury, or AKI) is an abrupt (typically detected within about 48 hours to 1 week) reduction in glomerular filtration. This loss of filtration capacity results in retention of nitrogenous (urea and creatinine) and non-nitrogenous waste products that are normally excreted by the kidney, a reduction in urine output, or both. It is reported that ARF complicates about 5% of hospital admissions, 4-15% of cardiopulmonary bypass surgeries, and up to 30% of intensive care admissions. ARF may be categorized as prerenal, intrinsic renal, or postrenal in causation. Intrinsic renal disease can be further divided into glomerular, tubular, interstitial, and vascular abnormalities. Major causes of ARF are described in the following table, which is adapted from the Merck Manual, 17 th  ed., Chapter 222, and which is hereby incorporated by reference in their entirety: 
     
       
         
           
               
               
             
               
                   
               
               
                 Type 
                 Risk Factors 
               
               
                   
               
             
            
               
                 Prerenal 
                   
               
               
                 ECF volume depletion 
                 Excessive diuresis, hemorrhage, GI losses, loss of 
               
               
                   
                 intravascular fluid into the extravascular space (due to 
               
               
                   
                 ascites, peritonitis, pancreatitis, or burns), loss of skin 
               
               
                   
                 and mucus membranes, renal salt- and water-wasting 
               
               
                   
                 states 
               
               
                 Low cardiac output 
                 Cardiomyopathy, MI, cardiac tamponade, pulmonary 
               
               
                   
                 embolism, pulmonary hypertension, positive-pressure 
               
               
                   
                 mechanical ventilation 
               
               
                 Low systemic vascular 
                 Septic shock, liver failure, antihypertensive drugs 
               
               
                 resistance 
               
               
                 Increased renal vascular 
                 NSAIDs, cyclosporines, tacrolimus, hypercalcemia, 
               
               
                 resistance 
                 anaphylaxis, anesthetics, renal artery obstruction, renal 
               
               
                   
                 vein thrombosis, sepsis, hepatorenal syndrome 
               
               
                 Decreased efferent 
                 ACE inhibitors or angiotensin II receptor blockers 
               
               
                 arteriolar tone (leading to 
               
               
                 decreased GFR from 
               
               
                 reduced glomerular 
               
               
                 transcapillary pressure, 
               
               
                 especially in patients with 
               
               
                 bilateral renal artery 
               
               
                 stenosis) 
               
               
                 Intrinsic Renal 
               
               
                 Acute tubular injury 
                 Ischemia (prolonged or severe prerenal state): surgery, 
               
               
                   
                 hemorrhage, arterial or venous obstruction; Toxins: 
               
               
                   
                 NSAIDs, cyclosporines, tacrolimus, aminoglycosides, 
               
               
                   
                 foscarnet, ethylene glycol, hemoglobin, myoglobin, 
               
               
                   
                 ifosfamide, heavy metals, methotrexate, radiopaque 
               
               
                   
                 contrast agents, streptozotocin 
               
               
                 Acute glomerulonephritis 
                 ANCA-associated: Crescentic glomerulonephritis, 
               
               
                   
                 polyarteritis nodosa, Wegener&#39;s granulomatosis; Anti- 
               
               
                   
                 GBM glomerulonephritis: Goodpasture&#39;s syndrome; 
               
               
                   
                 Immune-complex: Lupus glomerulonephritis, 
               
               
                   
                 postinfectious glomerulonephritis, cryoglobulinemic 
               
               
                   
                 glomerulonephritis 
               
               
                 Acute tubulointerstitial 
                 Drug reaction (eg, β-lactams, NSAIDs, sulfonamides, 
               
               
                 nephritis 
                 ciprofloxacin, thiazide diuretics, furosemide, phenytoin, 
               
               
                   
                 allopurinol, pyelonephritis, papillary necrosis 
               
               
                 Acute vascular 
                 Vasculitis, malignant hypertension, thrombotic 
               
               
                 nephropathy 
                 microangiopathies, scleroderma, atheroembolism 
               
               
                 Infiltrative diseases 
                 Lymphoma, sarcoidosis, leukemia 
               
               
                 Postrenal 
               
               
                 Tubular precipitation 
                 Uric acid (tumor lysis), sulfonamides, triamterene, 
               
               
                   
                 acyclovir, indinavir, methotrexate, ethylene glycol 
               
               
                   
                 ingestion, myeloma protein, myoglobin 
               
               
                 Ureteral obstruction 
                 Intrinsic: Calculi, clots, sloughed renal tissue, fungus 
               
               
                   
                 ball, edema, malignancy, congenital defects; Extrinsic: 
               
               
                   
                 Malignancy, retroperitoneal fibrosis, ureteral trauma 
               
               
                   
                 during surgery or high impact injury 
               
               
                 Bladder obstruction 
                 Mechanical: Benign prostatic hyperplasia, prostate 
               
               
                   
                 cancer, bladder cancer, urethral strictures, phimosis, 
               
               
                   
                 paraphimosis, urethral valves, obstructed indwelling 
               
               
                   
                 urinary catheter; Neurogenic: Anticholinergic drugs, 
               
               
                   
                 upper or lower motor neuron lesion 
               
               
                   
               
            
           
         
       
     
     In the case of ischemic ARF, the course of the disease may be divided into four phases. During an initiation phase, which lasts hours to days, reduced perfusion of the kidney is evolving into injury. Glomerular ultrafiltration reduces, the flow of filtrate is reduced due to debris within the tubules, and back leakage of filtrate through injured epithelium occurs. Renal injury can be mediated during this phase by reperfusion of the kidney. Initiation is followed by an extension phase which is characterized by continued ischemic injury and inflammation and may involve endothelial damage and vascular congestion. During the maintenance phase, lasting from 1 to 2 weeks, renal cell injury occurs, and glomerular filtration and urine output reaches a minimum. A recovery phase can follow in which the renal epithelium is repaired and GFR gradually recovers. Despite this, the survival rate of subjects with ARF may be as low as about 60%. 
     Acute kidney injury caused by radiocontrast agents (also called contrast media) and other nephrotoxins such as cyclosporine, antibiotics including aminoglycosides and anticancer drugs such as cisplatin manifests over a period of days to about a week. Contrast induced nephropathy (CIN, which is AKI caused by radiocontrast agents) is thought to be caused by intrarenal vasoconstriction (leading to ischemic injury) and from the generation of reactive oxygen species that are directly toxic to renal tubular epithelial cells. CIN classically presents as an acute (onset within 24-48h) but reversible (peak 3-5 days, resolution within 1 week) rise in blood urea nitrogen and serum creatinine. 
     A commonly reported criteria for defining and detecting AKI is an abrupt (typically within about 2-7 days or within a period of hospitalization) elevation of serum creatinine. Although the use of serum creatinine elevation to define and detect AKI is well established, the magnitude of the serum creatinine elevation and the time over which it is measured to define AKI varies considerably among publications. Traditionally, relatively large increases in serum creatinine such as 100%, 200%, an increase of at least 100% to a value over 2 mg/dL and other definitions were used to define AKI. However, the recent trend has been towards using smaller serum creatinine rises to define AKI. The relationship between serum creatinine rise, AKI and the associated health risks are reviewed in Praught and Shlipak,  Curr Opin Nephrol Hypertens  14:265-270, 2005 and Chertow et al,  J Am Soc Nephrol  16: 3365-3370, 2005, which, with the references listed therein, are hereby incorporated by reference in their entirety. As described in these publications, acute worsening renal function (AKI) and increased risk of death and other detrimental outcomes are now known to be associated with very small increases in serum creatinine. These increases may be determined as a relative (percent) value or a nominal value. Relative increases in serum creatinine as small as 20% from the pre-injury value have been reported to indicate acutely worsening renal function (AKI) and increased health risk, but the more commonly reported value to define AKI and increased health risk is a relative increase of at least 25%. Nominal increases as small as 0.3 mg/dL, 0.2 mg/dL or even 0.1 mg/dL have been reported to indicate worsening renal function and increased risk of death. Various time periods for the serum creatinine to rise to these threshold values have been used to define AKI, for example, ranging from 2 days, 3 days, 7 days, or a variable period defined as the time the patient is in the hospital or intensive care unit. These studies indicate there is not a particular threshold serum creatinine rise (or time period for the rise) for worsening renal function or AKI, but rather a continuous increase in risk with increasing magnitude of serum creatinine rise. 
     One study (Lassnigg et all, J Am Soc Nephrol 15:1597-1605, 2004, hereby incorporated by reference in its entirety) investigated both increases and decreases in serum creatinine. Patients with a mild fall in serum creatinine of −0.1 to −0.3 mg/dL following heart surgery had the lowest mortality rate. Patients with a larger fall in serum creatinine (more than or equal to −0.4 mg/dL) or any increase in serum creatinine had a larger mortality rate. These findings caused the authors to conclude that even very subtle changes in renal function (as detected by small creatinine changes within 48 hours of surgery) seriously effect patient&#39;s outcomes. In an effort to reach consensus on a unified classification system for using serum creatinine to define AKI in clinical trials and in clinical practice, Bellomo et al.,  Crit Care.  8(4):R204-12, 2004, which is hereby incorporated by reference in its entirety, proposes the following classifications for stratifying AKI patients: 
     “Risk”: serum creatinine increased 1.5 fold from baseline OR urine production of &lt;0.5 ml/kg body weight/hr for 6 hours;
 
“Injury”: serum creatinine increased 2.0 fold from baseline OR urine production &lt;0.5 ml/kg/hr for 12 h;
 
“Failure”: serum creatinine increased 3.0 fold from baseline OR creatinine &gt;355 μmol/l (with a rise of &gt;44) or urine output below 0.3 ml/kg/hr for 24 h or anuria for at least 12 hours;
 
And included two clinical outcomes:
 
“Loss”: persistent need for renal replacement therapy for more than four weeks.
 
“ESRD”: end stage renal disease—the need for dialysis for more than 3 months.
 
These criteria are called the RIFLE criteria, which provide a useful clinical tool to classify renal status. As discussed in Kellum,  Crit. Care Med.  36: S141-45, 2008 and Ricci et al.,  Kidney Int.  73, 538-546, 2008, each hereby incorporated by reference in its entirety, the RIFLE criteria provide a uniform definition of AKI which has been validated in numerous studies. For purposes of the present invention, “RIFLE stage 0” refers to a patient that does not fall within the RIFLE R, I or F criteria, and so is “pre-risk.”
 
More recently, Mehta et al.,  Crit. Care  11:R31 (doi:10.1186.cc5713), 2007, hereby incorporated by reference in its entirety, proposes the following similar classifications for stratifying AKI patients, which have been modified from RIFLE:
 
“Stage I”: increase in serum creatinine of more than or equal to 0.3 mg/dL (≧26.4 μmol/L) or increase to more than or equal to 150% (1.5-fold) from baseline OR urine output less than 0.5 mL/kg per hour for more than 6 hours;
 
“Stage II”: increase in serum creatinine to more than 200% (&gt;2-fold) from baseline OR urine output less than 0.5 mL/kg per hour for more than 12 hours;
 
“Stage III”: increase in serum creatinine to more than 300% (&gt;3-fold) from baseline OR serum creatinine ≧354 μmol/L accompanied by an acute increase of at least 44 μmol/L OR urine output less than 0.3 mL/kg per hour for 24 hours or anuria for 12 hours.
 
     The CIN Consensus Working Panel (McCollough et al, Rev Cardiovasc Med. 2006; 7(4):177-197, hereby incorporated by reference in its entirety) uses a serum creatinine rise of 25% to define Contrast induced nephropathy (which is a type of AKI).Although various groups propose slightly different criteria for using serum creatinine to detect AKI, the consensus is that small changes in serum creatinine, such as 0.3 mg/dL or 25%, are sufficient to detect AKI (worsening renal function) and that the magnitude of the serum creatinine change is an indicator of the severity of the AKI and mortality risk. 
     Although serial measurement of serum creatinine over a period of days is an accepted method of detecting and diagnosing AKI and is considered one of the most important tools to evaluate AKI patients, serum creatinine is generally regarded to have several limitations in the diagnosis, assessment and monitoring of AKI patients. The time period for serum creatinine to rise to values (e.g., a 0.3 mg/dL or 25% rise) considered diagnostic for AKI can be 48 hours or longer depending on the definition used. Since cellular injury in AKI can occur over a period of hours, serum creatinine elevations detected at 48 hours or longer can be a late indicator of injury, and relying on serum creatinine can thus delay diagnosis of AKI. Furthermore, serum creatinine is not a good indicator of the exact kidney status and treatment needs during the most acute phases of AKI when kidney function is changing rapidly. Some patients with AKI will recover fully, some will need dialysis (either short term or long term) and some will have other detrimental outcomes including death, major adverse cardiac events and chronic kidney disease. Because serum creatinine is a marker of filtration rate, it does not differentiate between the causes of AKI (pre-renal, intrinsic renal, post-renal obstruction, atheroembolic, etc) or the category or location of injury in intrinsic renal disease (for example, tubular, glomerular or interstitial in origin). Urine output is similarly limited, Knowing these things can be of vital importance in managing and treating patients with AKI. 
     These limitations underscore the need for better methods to detect and assess AKI, particularly in the early and subclinical stages, but also in later stages when recovery and repair of the kidney can occur. Furthermore, there is a need to better identify patients who are at risk of having an AKI. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to provide methods and compositions for evaluating renal function in a subject. As described herein, measurement of the kidney injury markers described herein can be used for diagnosis, prognosis, risk stratification, staging, monitoring, categorizing and determination of further diagnosis and treatment regimens in subjects suffering or at risk of suffering from an injury to renal function, reduced renal function, and/or acute renal failure (also called acute kidney injury). 
     These kidney injury markers may be used individually or in panels comprising a plurality of kidney injury markers, for risk stratification (that is, to identify subjects at risk for a future injury to renal function, for future progression to reduced renal function, for future progression to ARF, for future improvement in renal function, etc.); for diagnosis of existing disease (that is, to identify subjects who have suffered an injury to renal function, who have progressed to reduced renal function, who have progressed to ARF, etc.); for monitoring for deterioration or improvement of renal function; and for predicting a future medical outcome, such as improved or worsening renal function, a decreased or increased mortality risk, a decreased or increased risk that a subject will require initiation or continuation of renal replacement therapy (i.e., hemodialysis, peritoneal dialysis, hemofiltration, and/or renal transplantation, a decreased or increased risk that a subject will recover from an injury to renal function, a decreased or increased risk that a subject will recover from ARF, a decreased or increased risk that a subject will progress to end stage renal disease, a decreased or increased risk that a subject will progress to chronic renal failure, a decreased or increased risk that a subject will suffer rejection of a transplanted kidney, etc. 
     In a first aspect, the present invention relates to methods for evaluating renal status in a subject. These methods comprise performing an assay method that is configured to detect hyaluronic acid (HA) in a body fluid sample obtained from the subject. The assay result(s), for example a measured concentration of HA, is then correlated to the renal status of the subject. This correlation to renal status may include correlating the assay result(s) to one or more of risk stratification, diagnosis, prognosis, staging, classifying and monitoring of the subject as described herein. Thus, the present invention utilizes one or more kidney injury markers of the present invention for the evaluation of renal injury. Preferred subjects are those with relatively normal kidney function, including those not receiving renal replacement therapy. This includes subjects in RIFLE stage 0 or R at the time the sample being tested is obtained from the subject. 
     In certain embodiments, the methods for evaluating renal status described herein are methods for risk stratification of the subject; that is, assigning a likelihood of one or more future changes in renal status to the subject. In these embodiments, the assay result(s) is/are correlated to one or more such future changes. The following are preferred risk stratification embodiments. 
     In preferred risk stratification embodiments, these methods comprise determining a subject&#39;s risk for a future injury to renal function, and the assay result(s) is/are correlated to a likelihood of such a future injury to renal function. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of suffering a future injury to renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of suffering a future injury to renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. 
     In other preferred risk stratification embodiments, these methods comprise determining a subject&#39;s risk for future reduced renal function, and the assay result(s) is/are correlated to a likelihood of such reduced renal function. For example, the measured concentrations may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of suffering a future reduced renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of future reduced renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. 
     In still other preferred risk stratification embodiments, these methods comprise determining a subject&#39;s likelihood for a future improvement in renal function, and the assay result(s) is/are correlated to a likelihood of such a future improvement in renal function. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of a future improvement in renal function is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. For a “negative going” kidney injury marker, an increased likelihood of a future improvement in renal function is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. 
     In yet other preferred risk stratification embodiments, these methods comprise determining a subject&#39;s risk for progression to ARF, and the result(s) is/are correlated to a likelihood of such progression to ARF. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of progression to ARF is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of progression to ARF is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. 
     And in other preferred risk stratification embodiments, these methods comprise determining a subject&#39;s outcome risk, and the assay result(s) is/are correlated to a likelihood of the occurrence of a clinical outcome related to a renal injury suffered by the subject. For example, the measured concentration(s) may each be compared to a threshold value. For a “positive going” kidney injury marker, an increased likelihood of one or more of: acute kidney injury, progression to a worsening stage of AKI, mortality, a requirement for renal replacement therapy, a requirement for withdrawal of renal toxins, end stage renal disease, heart failure, stroke, myocardial infarction, progression to chronic kidney disease, etc., is assigned to the subject when the measured concentration is above the threshold, relative to a likelihood assigned when the measured concentration is below the threshold. For a “negative going” kidney injury marker, an increased likelihood of one or more of: acute kidney injury, progression to a worsening stage of AKI, mortality, a requirement for renal replacement therapy, a requirement for withdrawal of renal toxins, end stage renal disease, heart failure, stroke, myocardial infarction, progression to chronic kidney disease, etc., is assigned to the subject when the measured concentration is below the threshold, relative to a likelihood assigned when the measured concentration is above the threshold. 
     In such risk stratification embodiments, preferably the likelihood or risk assigned is that an event of interest is more or less likely to occur within 180 days of the time at which the body fluid sample is obtained from the subject. In particularly preferred embodiments, the likelihood or risk assigned relates to an event of interest occurring within a shorter time period such as 18 months, 120 days, 90 days, 60 days, 45 days, 30 days, 21 days, 14 days, 7 days, 5 days, 96 hours, 72 hours, 48 hours, 36 hours, 24 hours, 12 hours, or less. A risk at 0 hours of the time at which the body fluid sample is obtained from the subject is equivalent to diagnosis of a current condition. 
     In preferred risk stratification embodiments, the subject is selected for risk stratification based on the pre-existence in the subject of one or more known risk factors for prerenal, intrinsic renal, or postrenal ARF. For example, a subject undergoing or having undergone major vascular surgery, coronary artery bypass, or other cardiac surgery; a subject having pre-existing congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, glomerular filtration below the normal range, cirrhosis, serum creatinine above the normal range, or sepsis; or a subject exposed to NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin are all preferred subjects for monitoring risks according to the methods described herein. This list is not meant to be limiting. By “pre-existence” in this context is meant that the risk factor exists at the time the body fluid sample is obtained from the subject. In particularly preferred embodiments, a subject is chosen for risk stratification based on an existing diagnosis of injury to renal function, reduced renal function, or ARF. 
     In other embodiments, the methods for evaluating renal status described herein are methods for diagnosing a renal injury in the subject; that is, assessing whether or not a subject has suffered from an injury to renal function, reduced renal function, or ARF. In these embodiments, the assay result(s), for example a measured concentration of HA, is/are correlated to the occurrence or nonoccurrence of a change in renal status. The following are preferred diagnostic embodiments. 
     In preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of an injury to renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of such an injury. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury to renal function is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury to renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury to renal function is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury to renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold). 
     In other preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of reduced renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of an injury causing reduced renal function. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury causing reduced renal function is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury causing reduced renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury causing reduced renal function is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury causing reduced renal function may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold). 
     In yet other preferred diagnostic embodiments, these methods comprise diagnosing the occurrence or nonoccurrence of ARF, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of an injury causing ARF. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of ARF is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of ARF may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of ARF is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of ARF may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold). 
     In still other preferred diagnostic embodiments, these methods comprise diagnosing a subject as being in need of renal replacement therapy, and the assay result(s) is/are correlated to a need for renal replacement therapy. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury creating a need for renal replacement therapy is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal replacement therapy may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury creating a need for renal replacement therapy is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal replacement therapy may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold). 
     In still other preferred diagnostic embodiments, these methods comprise diagnosing a subject as being in need of renal transplantation, and the assay result(s0 is/are correlated to a need for renal transplantation. For example, each of the measured concentration(s) may be compared to a threshold value. For a positive going marker, an increased likelihood of the occurrence of an injury creating a need for renal transplantation is assigned to the subject when the measured concentration is above the threshold (relative to the likelihood assigned when the measured concentration is below the threshold); alternatively, when the measured concentration is below the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal transplantation may be assigned to the subject (relative to the likelihood assigned when the measured concentration is above the threshold). For a negative going marker, an increased likelihood of the occurrence of an injury creating a need for renal transplantation is assigned to the subject when the measured concentration is below the threshold (relative to the likelihood assigned when the measured concentration is above the threshold); alternatively, when the measured concentration is above the threshold, an increased likelihood of the nonoccurrence of an injury creating a need for renal transplantation may be assigned to the subject (relative to the likelihood assigned when the measured concentration is below the threshold). 
     In still other embodiments, the methods for evaluating renal status described herein are methods for monitoring a renal injury in the subject; that is, assessing whether or not renal function is improving or worsening in a subject who has suffered from an injury to renal function, reduced renal function, or ARF. In these embodiments, the assay result(s), for example a measured concentration of HA, is/are correlated to the occurrence or nonoccurrence of a change in renal status. The following are preferred monitoring embodiments. 
     In preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from an injury to renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject. 
     In other preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from reduced renal function, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject. 
     In yet other preferred monitoring embodiments, these methods comprise monitoring renal status in a subject suffering from acute renal failure, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject. 
     In other additional preferred monitoring embodiments, these methods comprise monitoring renal status in a subject at risk of an injury to renal function due to the pre-existence of one or more known risk factors for prerenal, intrinsic renal, or postrenal ARF, and the assay result(s) is/are correlated to the occurrence or nonoccurrence of a change in renal status in the subject. For example, the measured concentration(s) may be compared to a threshold value. For a positive going marker, when the measured concentration is above the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is below the threshold, an improvement of renal function may be assigned to the subject. For a negative going marker, when the measured concentration is below the threshold, a worsening of renal function may be assigned to the subject; alternatively, when the measured concentration is above the threshold, an improvement of renal function may be assigned to the subject. 
     In still other embodiments, the methods for evaluating renal status described herein are methods for classifying a renal injury in the subject; that is, determining whether a renal injury in a subject is prerenal, intrinsic renal, or postrenal; and/or further subdividing these classes into subclasses such as acute tubular injury, acute glomerulonephritis acute tubulointerstitial nephritis, acute vascular nephropathy, or infiltrative disease; and/or assigning a likelihood that a subject will progress to a particular RIFLE stage. In these embodiments, the assay result(s), for example a measured concentration of HA, is/are correlated to a particular class and/or subclass. The following are preferred classification embodiments. 
     In preferred classification embodiments, these methods comprise determining whether a renal injury in a subject is prerenal, intrinsic renal, or postrenal; and/or further subdividing these classes into subclasses such as acute tubular injury, acute glomerulonephritis acute tubulointerstitial nephritis, acute vascular nephropathy, or infiltrative disease; and/or assigning a likelihood that a subject will progress to a particular RIFLE stage, and the assay result(s) is/are correlated to the injury classification for the subject. For example, the measured concentration may be compared to a threshold value, and when the measured concentration is above the threshold, a particular classification is assigned; alternatively, when the measured concentration is below the threshold, a different classification may be assigned to the subject. 
     A variety of methods may be used by the skilled artisan to arrive at a desired threshold value for use in these methods. For example, the threshold value may be determined from a population of normal subjects by selecting a concentration representing the 75 th , 85 th , 90 th , 95 th , or 99 th  percentile of a kidney injury marker measured in such normal subjects. Alternatively, the threshold value may be determined from a “diseased” population of subjects, e.g., those suffering from an injury or having a predisposition for an injury (e.g., progression to ARF or some other clinical outcome such as death, dialysis, renal transplantation, etc.), by selecting a concentration representing the 75 th , 85 th , 90 th , 95 th , or 99 th  percentile of a kidney injury marker measured in such subjects. In another alternative, the threshold value may be determined from a prior measurement of a kidney injury marker in the same subject; that is, a temporal change in the level of a kidney injury marker in the subject may be used to assign risk to the subject. 
     The foregoing discussion is not meant to imply, however, that the kidney injury markers of the present invention must be compared to corresponding individual thresholds. Methods for combining assay results can comprise the use of multivariate logistical regression, loglinear modeling, neural network analysis, n-of-m analysis, decision tree analysis, calculating ratios of markers, etc. This list is not meant to be limiting. In these methods, a composite result which is determined by combining individual markers may be treated as if it is itself a marker; that is, a threshold may be determined for the composite result as described herein for individual markers, and the composite result for an individual patient compared to this threshold. 
     The ability of a particular test to distinguish two populations can be established using ROC analysis. For example, ROC curves established from a “first” subpopulation which is predisposed to one or more future changes in renal status, and a “second” subpopulation which is not so predisposed can be used to calculate a ROC curve, and the area under the curve provides a measure of the quality of the test. Preferably, the tests described herein provide a ROC curve area greater than 0.5, preferably at least 0.6, more preferably 0.7, still more preferably at least 0.8, even more preferably at least 0.9, and most preferably at least 0.95. 
     In certain aspects, the measured concentration of one or more kidney injury markers, or a composite of such markers, may be treated as continuous variables. For example, any particular concentration can be converted into a corresponding probability of a future reduction in renal function for the subject, the occurrence of an injury, a classification, etc. In yet another alternative, a threshold that can provide an acceptable level of specificity and sensitivity in separating a population of subjects into “bins” such as a “first” subpopulation (e.g., which is predisposed to one or more future changes in renal status, the occurrence of an injury, a classification, etc.) and a “second” subpopulation which is not so predisposed. A threshold value is selected to separate this first and second population by one or more of the following measures of test accuracy: 
     an odds ratio greater than 1, preferably at least about 2 or more or about 0.5 or less, more preferably at least about 3 or more or about 0.33 or less, still more preferably at least about 4 or more or about 0.25 or less, even more preferably at least about 5 or more or about 0.2 or less, and most preferably at least about 10 or more or about 0.1 or less;
 
a specificity of greater than 0.5, preferably at least about 0.6, more preferably at least about 0.7, still more preferably at least about 0.8, even more preferably at least about 0.9 and most preferably at least about 0.95, with a corresponding sensitivity greater than 0.2, preferably greater than about 0.3, more preferably greater than about 0.4, still more preferably at least about 0.5, even more preferably about 0.6, yet more preferably greater than about 0.7, still more preferably greater than about 0.8, more preferably greater than about 0.9, and most preferably greater than about 0.95;
 
a sensitivity of greater than 0.5, preferably at least about 0.6, more preferably at least about 0.7, still more preferably at least about 0.8, even more preferably at least about 0.9 and most preferably at least about 0.95, with a corresponding specificity greater than 0.2, preferably greater than about 0.3, more preferably greater than about 0.4, still more preferably at least about 0.5, even more preferably about 0.6, yet more preferably greater than about 0.7, still more preferably greater than about 0.8, more preferably greater than about 0.9, and most preferably greater than about 0.95;
 
at least about 75% sensitivity, combined with at least about 75% specificity;
 
a positive likelihood ratio (calculated as sensitivity/(1−specificity)) of greater than 1, at least about 2, more preferably at least about 3, still more preferably at least about 5, and most preferably at least about 10; or
 
a negative likelihood ratio (calculated as (1-sensitivity)/specificity) of less than 1, less than or equal to about 0.5, more preferably less than or equal to about 0.3, and most preferably less than or equal to about 0.1.
 
The term “about” in the context of any of the above measurements refers to +/−5% of a given measurement.
 
     Multiple thresholds may also be used to assess renal status in a subject. For example, a “first” subpopulation which is predisposed to one or more future changes in renal status, the occurrence of an injury, a classification, etc., and a “second” subpopulation which is not so predisposed can be combined into a single group. This group is then subdivided into three or more equal parts (known as tertiles, quartiles, quintiles, etc., depending on the number of subdivisions). An odds ratio is assigned to subjects based on which subdivision they fall into. If one considers a tertile, the lowest or highest tertile can be used as a reference for comparison of the other subdivisions. This reference subdivision is assigned an odds ratio of 1. The second tertile is assigned an odds ratio that is relative to that first tertile. That is, someone in the second tertile might be 3 times more likely to suffer one or more future changes in renal status in comparison to someone in the first tertile. The third tertile is also assigned an odds ratio that is relative to that first tertile. 
     In certain embodiments, the assay method is an immunoassay. Antibodies for use in such assays will specifically bind a full length kidney injury marker of interest, and may also bind one or more polypeptides that are “related” thereto, as that term is defined hereinafter. Numerous immunoassay formats are known to those of skill in the art. Preferred body fluid samples are selected from the group consisting of urine, blood, serum, saliva, tears, and plasma. 
     The foregoing method steps should not be interpreted to mean that the kidney injury marker assay result(s) is/are used in isolation in the methods described herein. Rather, additional variables or other clinical indicia may be included in the methods described herein. For example, a risk stratification, diagnostic, classification, monitoring, etc. method may combine the assay result(s) with one or more variables measured for the subject selected from the group consisting of demographic information (e.g., weight, sex, age, race), medical history (e.g., family history, type of surgery, pre-existing disease such as aneurism, congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, or sepsis, type of toxin exposure such as NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin), clinical variables (e.g., blood pressure, temperature, respiration rate), risk scores (APACHE score, PREDICT score, TIMI Risk Score for UA/NSTEMI, Framingham Risk Score), a glomerular filtration rate, an estimated glomerular filtration rate, a urine production rate, a serum or plasma creatinine concentration, a urine creatinine concentration, a fractional excretion of sodium, a urine sodium concentration, a urine creatinine to serum or plasma creatinine ratio, a urine specific gravity, a urine osmolality, a urine urea nitrogen to plasma urea nitrogen ratio, a plasma BUN to creatnine ratio, a renal failure index calculated as urine sodium/(urine creatinine/plasma creatinine), a serum or plasma neutrophil gelatinase (NGAL) concentration, a urine NGAL concentration, a serum or plasma cystatin C concentration, a serum or plasma cardiac troponin concentration, a serum or plasma BNP concentration, a serum or plasma NTproBNP concentration, and a serum or plasma proBNP concentration. Other measures of renal function which may be combined with one or more kidney injury marker assay result(s) are described hereinafter and in Harrison&#39;s Principles of Internal Medicine, 17 th  Ed., McGraw Hill, New York, pages 1741-1830, and Current Medical Diagnosis &amp; Treatment 2008, 47 th  Ed, McGraw Hill, New York, pages 785-815, each of which are hereby incorporated by reference in their entirety. 
     When more than one marker is measured, the individual markers may be measured in samples obtained at the same time, or may be determined from samples obtained at different (e.g., an earlier or later) times. The individual markers may also be measured on the same or different body fluid samples. For example, one kidney injury marker may be measured in a serum or plasma sample and another kidney injury marker may be measured in a urine sample. In addition, assignment of a likelihood may combine an individual kidney injury marker assay result with temporal changes in one or more additional variables. 
     In various related aspects, the present invention also relates to devices and kits for performing the methods described herein. Suitable kits comprise reagents sufficient for performing an assay for at least one of the described kidney injury markers, together with instructions for performing the described threshold comparisons. 
     In certain embodiments, reagents for performing such assays are provided in an assay device, and such assay devices may be included in such a kit. Preferred reagents can comprise one or more solid phase antibodies, the solid phase antibody comprising antibody that detects the intended biomarker target(s) bound to a solid support. In the case of sandwich immunoassays, such reagents can also include one or more detectably labeled antibodies, the detectably labeled antibody comprising antibody that detects the intended biomarker target(s) bound to a detectable label. Additional optional elements that may be provided as part of an assay device are described hereinafter. 
     Detectable labels may include molecules that are themselves detectable (e.g., fluorescent moieties, electrochemical labels, ecl (electrochemical luminescence) labels, metal chelates, colloidal metal particles, etc.) as well as molecules that may be indirectly detected by production of a detectable reaction product (e.g., enzymes such as horseradish peroxidase, alkaline phosphatase, etc.) or through the use of a specific binding molecule which itself may be detectable (e.g., a labeled antibody that binds to the second antibody, biotin, digoxigenin, maltose, oligohistidine, 2,4-dintrobenzene, phenylarsenate, ssDNA, dsDNA, etc.). 
     Generation of a signal from the signal development element can be performed using various optical, acoustical, and electrochemical methods well known in the art. Examples of detection modes include fluorescence, radiochemical detection, reflectance, absorbance, amperometry, conductance, impedance, interferometry, ellipsometry, etc. In certain of these methods, the solid phase antibody is coupled to a transducer (e.g., a diffraction grating, electrochemical sensor, etc) for generation of a signal, while in others, a signal is generated by a transducer that is spatially separate from the solid phase antibody (e.g., a fluorometer that employs an excitation light source and an optical detector). This list is not meant to be limiting. Antibody-based biosensors may also be employed to determine the presence or amount of analytes that optionally eliminate the need for a labeled molecule. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  depicts the change in normalized urinary concentration of hyaluronic acid in response to a chemically induced acute kidney injury. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to methods and compositions for diagnosis, differential diagnosis, risk stratification, monitoring, classifying and determination of treatment regimens in subjects suffering or at risk of suffering from injury to renal function, reduced renal function and/or acute renal failure through measurement of one or more kidney injury markers of the present invention. 
     The following is a brief description of the kidney injury marker of the present invention. 
     Hyaluronic acid (HA) is a ubiquitous connective tissue glycosaminoglycan that in vivo is present as a high molecular mass component of most extracellular matrices. Although HA is not a major constituent of the normal renal corticointerstitium,3 it is expressed around renal proximal tubular epithelial cells (PTC) after both acute and chronic renal injury that is caused by numerous diseases.4, 5 Furthermore, increased deposition of interstitial HA correlates with both proteinuria and renal function in progressive renal disease.6 Binding of HA to its principle receptor, CD44, promotes inflammation through interaction between HA and CD44, expressed on inflammatory cells.7 HA/CD44 binding activates the mitogen-activated protein kinase (MAPK) pathway and enhances PTC migration, a process that is implicated in epithelial cell-fibroblast transdifferentiation and progressive renal fibrosis.8 In ischemic kidneys from diabetic subjects, the renal HA-content started to increases already after 24 hours and significantly so 1-8 weeks after ischemia/reperfusion (I/R).9 
     For purposes of this document, the following definitions apply: 
     As used herein, an “injury to renal function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) measurable reduction in a measure of renal function. Such an injury may be identified, for example, by a decrease in glomerular filtration rate or estimated GFR, a reduction in urine output, an increase in serum creatinine, an increase in serum cystatin C, a requirement for renal replacement therapy, etc. “Improvement in Renal Function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) measurable increase in a measure of renal function. Preferred methods for measuring and/or estimating GFR are described hereinafter. 
     As used herein, “reduced renal function” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) reduction in kidney function identified by an absolute increase in serum creatinine of greater than or equal to 0.1 mg/dL (≧8.8 μmol/L), a percentage increase in serum creatinine of greater than or equal to 20% (1.2-fold from baseline), or a reduction in urine output (documented oliguria of less than 0.5 ml/kg per hour). 
     As used herein, “acute renal failure” or “ARF” is an abrupt (within 14 days, preferably within 7 days, more preferably within 72 hours, and still more preferably within 48 hours) reduction in kidney function identified by an absolute increase in serum creatinine of greater than or equal to 0.3 mg/dl (&gt;26.4 μmol/l), a percentage increase in serum creatinine of greater than or equal to 50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria of less than 0.5 ml/kg per hour for at least 6 hours). This term is synonymous with “acute kidney injury” or “AKI.” 
     In this regard, the skilled artisan will understand that the signals obtained from an immunoassay are a direct result of complexes formed between one or more antibodies and the target biomolecule (i.e., the analyte) and polypeptides containing the necessary epitope(s) to which the antibodies bind. While such assays may detect the full length biomarker and the assay result be expressed as a concentration of a biomarker of interest, the signal from the assay is actually a result of all such “immunoreactive” polypeptides present in the sample. Expression of biomarkers may also be determined by means other than immunoassays, including protein measurements (such as dot blots, western blots, chromatographic methods, mass spectrometry, etc.) and nucleic acid measurements (mRNA quantitation). This list is not meant to be limiting. 
     As used herein, the term “relating a signal to the presence or amount” of an analyte reflects this understanding. Assay signals are typically related to the presence or amount of an analyte through the use of a standard curve calculated using known concentrations of the analyte of interest. The skilled artisan will understand that the signals obtained from an assay are often a direct result of complexes formed between one or more antibodies and the target biomolecule (i.e., the analyte) and polypeptides containing the necessary epitope(s) to which the antibodies bind. While such assays may detect the full length biomarker and the assay result be expressed as a concentration of a biomarker of interest, the signal from the assay is actually a result of all such “immunoreactive” polypeptides present in the sample. Expression of biomarkers may also be determined by means other than immunoassays, including protein measurements (such as dot blots, western blots, chromatographic methods, mass spectrometry, etc.) and nucleic acid measurements (mRNA quantitation). This list is not meant to be limiting. 
     As the term is used herein, an assay is “configured to detect” an analyte if an assay can generate a detectable signal indicative of the presence or amount of a physiologically relevant concentration of the analyte. Because an antibody epitope is on the order of 8 amino acids, an immunoassay configured to detect a marker of interest will also detect polypeptides related to the marker sequence, so long as those polypeptides contain the epitope(s) necessary to bind to the antibody or antibodies used in the assay. The term “related marker” as used herein with regard to a biomarker such as one of the kidney injury markers described herein refers to one or more fragments, variants, etc., of a particular marker or its biosynthetic parent that may be detected as a surrogate for the marker itself or as independent biomarkers. The term also refers to one or more polypeptides present in a biological sample that are derived from the biomarker precursor complexed to additional species, such as binding proteins, receptors, heparin, lipids, sugars, etc. 
     The term “positive going” marker as that term is used herein refer to a marker that is determined to be elevated in subjects suffering from a disease or condition, relative to subjects not suffering from that disease or condition. The term “negative going” marker as that term is used herein refer to a marker that is determined to be reduced in subjects suffering from a disease or condition, relative to subjects not suffering from that disease or condition. 
     The term “subject” as used herein refers to a human or non-human organism. Thus, the methods and compositions described herein are applicable to both human and veterinary disease. Further, while a subject is preferably a living organism, the invention described herein may be used in post-mortem analysis as well. Preferred subjects are humans, and most preferably “patients,” which as used herein refers to living humans that are receiving medical care for a disease or condition. This includes persons with no defined illness who are being investigated for signs of pathology. 
     Preferably, an analyte is measured in a sample. Such a sample may be obtained from a subject, or may be obtained from biological materials intended to be provided to the subject. For example, a sample may be obtained from a kidney being evaluated for possible transplantation into a subject, and an analyte measurement used to evaluate the kidney for preexisting damage. Preferred samples are body fluid samples. 
     The term “body fluid sample” as used herein refers to a sample of bodily fluid obtained for the purpose of diagnosis, prognosis, classification or evaluation of a subject of interest, such as a patient or transplant donor. In certain embodiments, such a sample may be obtained for the purpose of determining the outcome of an ongoing condition or the effect of a treatment regimen on a condition. Preferred body fluid samples include blood, serum, plasma, cerebrospinal fluid, urine, saliva, sputum, and pleural effusions. In addition, one of skill in the art would realize that certain body fluid samples would be more readily analyzed following a fractionation or purification procedure, for example, separation of whole blood into serum or plasma components. 
     The term “diagnosis” as used herein refers to methods by which the skilled artisan can estimate and/or determine the probability (“a likelihood”) of whether or not a patient is suffering from a given disease or condition. In the case of the present invention, “diagnosis” includes using the results of an assay, most preferably an immunoassay, for a kidney injury marker of the present invention, optionally together with other clinical characteristics, to arrive at a diagnosis (that is, the occurrence or nonoccurrence) of an acute renal injury or ARF for the subject from which a sample was obtained and assayed. That such a diagnosis is “determined” is not meant to imply that the diagnosis is 100% accurate. Many biomarkers are indicative of multiple conditions. The skilled clinician does not use biomarker results in an informational vacuum, but rather test results are used together with other clinical indicia to arrive at a diagnosis. Thus, a measured biomarker level on one side of a predetermined diagnostic threshold indicates a greater likelihood of the occurrence of disease in the subject relative to a measured level on the other side of the predetermined diagnostic threshold. 
     Similarly, a prognostic risk signals a probability (“a likelihood”) that a given course or outcome will occur. A level or a change in level of a prognostic indicator, which in turn is associated with an increased probability of morbidity (e.g., worsening renal function, future ARF, or death) is referred to as being “indicative of an increased likelihood” of an adverse outcome in a patient. 
     Marker Assays 
     In general, immunoassays involve contacting a sample containing or suspected of containing a biomarker of interest with at least one antibody that specifically binds to the biomarker. A signal is then generated indicative of the presence or amount of complexes formed by the binding of polypeptides in the sample to the antibody. The signal is then related to the presence or amount of the biomarker in the sample. Numerous methods and devices are well known to the skilled artisan for the detection and analysis of biomarkers. See, e.g., U.S. Pat. Nos. 6,143,576; 6,113,855; 6,019,944; 5,985,579; 5,947,124; 5,939,272; 5,922,615; 5,885,527; 5,851,776; 5,824,799; 5,679,526; 5,525,524; and 5,480,792, and The Immunoassay Handbook, David Wild, ed. Stockton Press, New York, 1994, each of which is hereby incorporated by reference in its entirety, including all tables, figures and claims. 
     The assay devices and methods known in the art can utilize labeled molecules in various sandwich, competitive, or non-competitive assay formats, to generate a signal that is related to the presence or amount of the biomarker of interest. Suitable assay formats also include chromatographic, mass spectrographic, and protein “blotting” methods. Additionally, certain methods and devices, such as biosensors and optical immunoassays, may be employed to determine the presence or amount of analytes without the need for a labeled molecule. See, e.g., U.S. Pat. Nos. 5,631,171; and 5,955,377, each of which is hereby incorporated by reference in its entirety, including all tables, figures and claims. One skilled in the art also recognizes that robotic instrumentation including but not limited to Beckman ACCESS®, Abbott AXSYM®, Roche ELECSYS®, Dade Behring STRATUS® systems are among the immunoassay analyzers that are capable of performing immunoassays. But any suitable immunoassay may be utilized, for example, enzyme-linked immunoassays (ELISA), radioimmunoassays (RIAs), competitive binding assays, and the like. 
     Antibodies or other polypeptides may be immobilized onto a variety of solid supports for use in assays. Solid phases that may be used to immobilize specific binding members include those developed and/or used as solid phases in solid phase binding assays. Examples of suitable solid phases include membrane filters, cellulose-based papers, beads (including polymeric, latex and paramagnetic particles), glass, silicon wafers, microparticles, nanoparticles, TentaGels, AgroGels, PEGA gels, SPOCC gels, and multiple-well plates. An assay strip could be prepared by coating the antibody or a plurality of antibodies in an array on solid support. This strip could then be dipped into the test sample and then processed quickly through washes and detection steps to generate a measurable signal, such as a colored spot. Antibodies or other polypeptides may be bound to specific zones of assay devices either by conjugating directly to an assay device surface, or by indirect binding. In an example of the later case, antibodies or other polypeptides may be immobilized on particles or other solid supports, and that solid support immobilized to the device surface. 
     Biological assays require methods for detection, and one of the most common methods for quantitation of results is to conjugate a detectable label to a protein or nucleic acid that has affinity for one of the components in the biological system being studied. Detectable labels may include molecules that are themselves detectable (e.g., fluorescent moieties, electrochemical labels, metal chelates, etc.) as well as molecules that may be indirectly detected by production of a detectable reaction product (e.g., enzymes such as horseradish peroxidase, alkaline phosphatase, etc.) or by a specific binding molecule which itself may be detectable (e.g., biotin, digoxigenin, maltose, oligohistidine, 2,4-dintrobenzene, phenylarsenate, ssDNA, dsDNA, etc.). 
     Preparation of solid phases and detectable label conjugates often comprise the use of chemical cross-linkers. Cross-linking reagents contain at least two reactive groups, and are divided generally into homofunctional cross-linkers (containing identical reactive groups) and heterofunctional cross-linkers (containing non-identical reactive groups). Homobifunctional cross-linkers that couple through amines, sulfhydryls or react non-specifically are available from many commercial sources. Maleimides, alkyl and aryl halides, alpha-haloacyls and pyridyl disulfides are thiol reactive groups. Maleimides, alkyl and aryl halides, and alpha-haloacyls react with sulfhydryls to form thiol ether bonds, while pyridyl disulfides react with sulfhydryls to produce mixed disulfides. The pyridyl disulfide product is cleavable. Imidoesters are also very useful for protein-protein cross-links. A variety of heterobifunctional cross-linkers, each combining different attributes for successful conjugation, are commercially available. 
     In certain aspects, the present invention provides kits for the analysis of the described kidney injury markers. The kit comprises reagents for the analysis of at least one test sample which comprise at least one antibody that a kidney injury marker. The kit can also include devices and instructions for performing one or more of the diagnostic and/or prognostic correlations described herein. Preferred kits will comprise an antibody pair for performing a sandwich assay, or a labeled species for performing a competitive assay, for the analyte. Preferably, an antibody pair comprises a first antibody conjugated to a solid phase and a second antibody conjugated to a detectable label, wherein each of the first and second antibodies that bind a kidney injury marker. Most preferably each of the antibodies are monoclonal antibodies. The instructions for use of the kit and performing the correlations can be in the form of labeling, which refers to any written or recorded material that is attached to, or otherwise accompanies a kit at any time during its manufacture, transport, sale or use. For example, the term labeling encompasses advertising leaflets and brochures, packaging materials, instructions, audio or video cassettes, computer discs, as well as writing imprinted directly on kits. 
     Antibodies 
     The term “antibody” as used herein refers to a peptide or polypeptide derived from, modeled after or substantially encoded by an immunoglobulin gene or immunoglobulin genes, or fragments thereof, capable of specifically binding an antigen or epitope. See, e.g. Fundamental Immunology, 3rd Edition, W. E. Paul, ed., Raven Press, N.Y. (1993); Wilson (1994; J. Immunol. Methods 175:267-273; Yarmush (1992) J. Biochem. Biophys. Methods 25:85-97. The term antibody includes antigen-binding portions, i.e., “antigen binding sites,” (e.g., fragments, subsequences, complementarity determining regions (CDRs)) that retain capacity to bind antigen, including (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains; (ii) a F(ab′)2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341:544-546), which consists of a VH domain; and (vi) an isolated complementarity determining region (CDR). Single chain antibodies are also included by reference in the term “antibody.” 
     Antibodies used in the immunoassays described herein preferably specifically bind to a kidney injury marker of the present invention. The term “specifically binds” is not intended to indicate that an antibody binds exclusively to its intended target since, as noted above, an antibody binds to any polypeptide displaying the epitope(s) to which the antibody binds. Rather, an antibody “specifically binds” if its affinity for its intended target is about 5-fold greater when compared to its affinity for a non-target molecule which does not display the appropriate epitope(s). Preferably the affinity of the antibody will be at least about 5 fold, preferably 10 fold, more preferably 25-fold, even more preferably 50-fold, and most preferably 100-fold or more, greater for a target molecule than its affinity for a non-target molecule. In preferred embodiments, Preferred antibodies bind with affinities of at least about 10 7  M −1 , and preferably between about 10 8  M −1  to about 10 9  M −1 , about 10 9  M −1  to about 10 10  M −1 , or about 10 M −1  to about 10 12  M −1 . 
     Affinity is calculated as K d =k off /k on  (k off  is the dissociation rate constant, K on  is the association rate constant and K d  is the equilibrium constant). Affinity can be determined at equilibrium by measuring the fraction bound (r) of labeled ligand at various concentrations (c). The data are graphed using the Scatchard equation: r/c=K(n−r): where r=moles of bound ligand/mole of receptor at equilibrium; c=free ligand concentration at equilibrium; K=equilibrium association constant; and n=number of ligand binding sites per receptor molecule. By graphical analysis, r/c is plotted on the Y-axis versus r on the X-axis, thus producing a Scatchard plot. Antibody affinity measurement by Scatchard analysis is well known in the art. See, e.g., van Erp et al.,  J. Immunoassay  12: 425-43, 1991; Nelson and Griswold,  Comput. Methods Programs Biomed.  27: 65-8, 1988. 
     The term “epitope” refers to an antigenic determinant capable of specific binding to an antibody. Epitopes usually consist of chemically active surface groupings of molecules such as amino acids or sugar side chains and usually have specific three dimensional structural characteristics, as well as specific charge characteristics. Conformational and nonconformational epitopes are distinguished in that the binding to the former but not the latter is lost in the presence of denaturing solvents. 
     Numerous publications discuss the use of phage display technology to produce and screen libraries of polypeptides for binding to a selected analyte. See, e.g, Cwirla et al.,  Proc. Natl. Acad. Sci. USA  87, 6378-82, 1990; Devlin et al.,  Science  249, 404-6, 1990, Scott and Smith,  Science  249, 386-88, 1990; and Ladner et al., U.S. Pat. No. 5,571,698. A basic concept of phage display methods is the establishment of a physical association between DNA encoding a polypeptide to be screened and the polypeptide. This physical association is provided by the phage particle, which displays a polypeptide as part of a capsid enclosing the phage genome which encodes the polypeptide. The establishment of a physical association between polypeptides and their genetic material allows simultaneous mass screening of very large numbers of phage bearing different polypeptides. Phage displaying a polypeptide with affinity to a target bind to the target and these phage are enriched by affinity screening to the target. The identity of polypeptides displayed from these phage can be determined from their respective genomes. Using these methods a polypeptide identified as having a binding affinity for a desired target can then be synthesized in bulk by conventional means. See, e.g., U.S. Pat. No. 6,057,098, which is hereby incorporated in its entirety, including all tables, figures, and claims. 
     The antibodies that are generated by these methods may then be selected by first screening for affinity and specificity with the purified polypeptide of interest and, if required, comparing the results to the affinity and specificity of the antibodies with polypeptides that are desired to be excluded from binding. The screening procedure can involve immobilization of the purified polypeptides in separate wells of microtiter plates. The solution containing a potential antibody or groups of antibodies is then placed into the respective microtiter wells and incubated for about 30 min to 2 h. The microtiter wells are then washed and a labeled secondary antibody (for example, an anti-mouse antibody conjugated to alkaline phosphatase if the raised antibodies are mouse antibodies) is added to the wells and incubated for about 30 min and then washed. Substrate is added to the wells and a color reaction will appear where antibody to the immobilized polypeptide(s) are present. 
     The antibodies so identified may then be further analyzed for affinity and specificity in the assay design selected. In the development of immunoassays for a target protein, the purified target protein acts as a standard with which to judge the sensitivity and specificity of the immunoassay using the antibodies that have been selected. Because the binding affinity of various antibodies may differ; certain antibody pairs (e.g., in sandwich assays) may interfere with one another sterically, etc., assay performance of an antibody may be a more important measure than absolute affinity and specificity of an antibody. 
     Assay Correlations 
     The term “correlating” as used herein in reference to the use of biomarkers refers to comparing the presence or amount of the biomarker(s) in a patient to its presence or amount in persons known to suffer from, or known to be at risk of, a given condition; or in persons known to be free of a given condition. Often, this takes the form of comparing an assay result in the form of a biomarker concentration to a predetermined threshold selected to be indicative of the occurrence or nonoccurrence of a disease or the likelihood of some future outcome. 
     Selecting a diagnostic threshold involves, among other things, consideration of the probability of disease, distribution of true and false diagnoses at different test thresholds, and estimates of the consequences of treatment (or a failure to treat) based on the diagnosis. For example, when considering administering a specific therapy which is highly efficacious and has a low level of risk, few tests are needed because clinicians can accept substantial diagnostic uncertainty. On the other hand, in situations where treatment options are less effective and more risky, clinicians often need a higher degree of diagnostic certainty. Thus, cost/benefit analysis is involved in selecting a diagnostic threshold. 
     Suitable thresholds may be determined in a variety of ways. For example, one recommended diagnostic threshold for the diagnosis of acute myocardial infarction using cardiac troponin is the 97.5 th  percentile of the concentration seen in a normal population. Another method may be to look at serial samples from the same patient, where a prior “baseline” result is used to monitor for temporal changes in a biomarker level. 
     Population studies may also be used to select a decision threshold. Receiver Operating Characteristic (“ROC”) arose from the field of signal detection theory developed during World War II for the analysis of radar images, and ROC analysis is often used to select a threshold able to best distinguish a “diseased” subpopulation from a “nondiseased” subpopulation. A false positive in this case occurs when the person tests positive, but actually does not have the disease. A false negative, on the other hand, occurs when the person tests negative, suggesting they are healthy, when they actually do have the disease. To draw a ROC curve, the true positive rate (TPR) and false positive rate (FPR) are determined as the decision threshold is varied continuously. Since TPR is equivalent with sensitivity and FPR is equal to 1−specificity, the ROC graph is sometimes called the sensitivity vs (1−specificity) plot. A perfect test will have an area under the ROC curve of 1.0; a random test will have an area of 0.5. A threshold is selected to provide an acceptable level of specificity and sensitivity. 
     In this context, “diseased” is meant to refer to a population having one characteristic (the presence of a disease or condition or the occurrence of some outcome) and “nondiseased” is meant to refer to a population lacking the characteristic. While a single decision threshold is the simplest application of such a method, multiple decision thresholds may be used. For example, below a first threshold, the absence of disease may be assigned with relatively high confidence, and above a second threshold the presence of disease may also be assigned with relatively high confidence. Between the two thresholds may be considered indeterminate. This is meant to be exemplary in nature only. 
     In addition to threshold comparisons, other methods for correlating assay results to a patient classification (occurrence or nonoccurrence of disease, likelihood of an outcome, etc.) include decision trees, rule sets, Bayesian methods, and neural network methods. These methods can produce probability values representing the degree to which a subject belongs to one classification out of a plurality of classifications. 
     Measures of test accuracy may be obtained as described in Fischer et al.,  Intensive Care Med.  29: 1043-51, 2003, and used to determine the effectiveness of a given biomarker. These measures include sensitivity and specificity, predictive values, likelihood ratios, diagnostic odds ratios, and ROC curve areas. The area under the curve (“AUC”) of a ROC plot is equal to the probability that a classifier will rank a randomly chosen positive instance higher than a randomly chosen negative one. The area under the ROC curve may be thought of as equivalent to the Mann-Whitney U test, which tests for the median difference between scores obtained in the two groups considered if the groups are of continuous data, or to the Wilcoxon test of ranks. 
     As discussed above, suitable tests may exhibit one or more of the following results on these various measures: a specificity of greater than 0.5, preferably at least 0.6, more preferably at least 0.7, still more preferably at least 0.8, even more preferably at least 0.9 and most preferably at least 0.95, with a corresponding sensitivity greater than 0.2, preferably greater than 0.3, more preferably greater than 0.4, still more preferably at least 0.5, even more preferably 0.6, yet more preferably greater than 0.7, still more preferably greater than 0.8, more preferably greater than 0.9, and most preferably greater than 0.95; a sensitivity of greater than 0.5, preferably at least 0.6, more preferably at least 0.7, still more preferably at least 0.8, even more preferably at least 0.9 and most preferably at least 0.95, with a corresponding specificity greater than 0.2, preferably greater than 0.3, more preferably greater than 0.4, still more preferably at least 0.5, even more preferably 0.6, yet more preferably greater than 0.7, still more preferably greater than 0.8, more preferably greater than 0.9, and most preferably greater than 0.95; at least 75% sensitivity, combined with at least 75% specificity; a ROC curve area of greater than 0.5, preferably at least 0.6, more preferably 0.7, still more preferably at least 0.8, even more preferably at least 0.9, and most preferably at least 0.95; an odds ratio different from 1, preferably at least about 2 or more or about 0.5 or less, more preferably at least about 3 or more or about 0.33 or less, still more preferably at least about 4 or more or about 0.25 or less, even more preferably at least about 5 or more or about 0.2 or less, and most preferably at least about 10 or more or about 0.1 or less; a positive likelihood ratio (calculated as sensitivity/(1−specificity)) of greater than 1, at least 2, more preferably at least 3, still more preferably at least 5, and most preferably at least 10; and or a negative likelihood ratio (calculated as (1-sensitivity)/specificity) of less than 1, less than or equal to 0.5, more preferably less than or equal to 0.3, and most preferably less than or equal to 0.1 
     Additional clinical indicia may be combined with the kidney injury marker assay result(s) of the present invention. These include other biomarkers related to renal status. Examples include the following, which recite the common biomarker name, followed by the Swiss-Prot entry number for that biomarker or its parent: Actin (P68133); Adenosine deaminase binding protein (DPP4, P27487); Alpha-1-acid glycoprotein 1 (P02763); Alpha-1-microglobulin (P02760); Albumin (P02768); Angiotensinogenase (Renin, P00797); Annexin A2 (P07355); Beta-glucuronidase (P08236); B-2-microglobulin (P61679); Beta-galactosidase (P16278); BMP-7 (P18075); Brain natriuretic peptide (proBNP, BNP-32, NTproBNP; P16860); Calcium-binding protein Beta (S100-beta, P04271); Carbonic anhydrase (Q16790); Casein Kinase 2 (P68400); Cadherin-3 (P07858); Ceruloplasmin (P00450); Clusterin (P10909); Complement C3 (P01024); Cysteine-rich protein (CYR61, 000622); Cytochrome C(P99999); Epidermal growth factor (EGF, P01133); Endothelin-1 (P05305); Exosomal Fetuin-A (P02765); Fatty acid-binding protein, heart (FABP3, P05413); Fatty acid-binding protein, liver (P07148); Ferritin (light chain, P02793; heavy chain P02794); Fructose-1,6-biphosphatase (P09467); GRO-alpha (CXCL1, (P09341); Growth Hormone (P01241); Hepatocyte growth factor (P14210); Insulin-like growth factor I (P01343); Immunoglobulin G; Immunoglobulin Light Chains (Kappa and Lambda); Interferon gamma (P01308); Lysozyme (P61626); Interleukin-1alpha (P01583); Interleukin-2 (P60568); Interleukin-4 (P60568); Interleukin-9 (P15248); Interleukin-12p40 (P29460); Interleukin-13 (P35225); Interleukin-16 (Q14005); L1 cell adhesion molecule (P32004); Lactate dehydrogenase (P00338); Leucine Aminopeptidase (P28838); Meprin A-alpha subunit (Q16819); Meprin A-beta subunit (Q16820); Midkine (P21741); MIP2-alpha (CXCL2, P19875); MMP-2 (P08253); MMP-9 (P14780); Netrin-1 (095631); Neutral endopeptidase (P08473); Osteopontin (P10451); Renal papillary antigen 1 (RPA1); Renal papillary antigen 2 (RPA2); Retinol binding protein (P09455); Ribonuclease; S100 calcium-binding protein A6 (P06703); Serum Amyloid P Component (P02743); Sodium/Hydrogen exchanger isoform (NHE3, P48764); Spermidine/spermine N1-acetyltransferase (P21673); TGF-Beta1 (P01137); Transferrin (P02787); Trefoil factor 3 (TFF3, Q07654); Toll-Like protein 4 (O00206); Total protein; Tubulointerstitial nephritis antigen (Q9UJW2); Uromodulin (Tamm-Horsfall protein, P07911). 
     For purposes of risk stratification, Adiponectin (Q15848); Alkaline phosphatase (P05186); Aminopeptidase N(P15144); CalbindinD28k (P05937); Cystatin C(P01034); 8 subunit of FIFO ATPase (P03928); Gamma-glutamyltransferase (P19440); GSTa (alpha-glutathione-S-transferase, P08263); GSTpi (Glutathione-S-transferase P; GST class-pi; P09211); IGFBP-1 (P08833); IGFBP-2 (P18065); IGFBP-6 (P24592); Integral membrane protein 1 (Itm1, P46977); Interleukin-6 (P05231); Interleukin-8 (P10145); Interleukin-18 (Q14116); IP-10 (10 kDa interferon-gamma-induced protein, P02778); IRPR (IFRD1, O00458); Isovaleryl-CoA dehydrogenase (IVD, P26440); I-TAC/CXCL11 (O14625); Keratin 19 (P08727); Kim-1 (Hepatitis A virus cellular receptor 1, O43656); L-arginine:glycine amidinotransferase (P50440); Leptin (P41159); Lipocalin2 (NGAL, P80188); MCP-1 (P13500); MIG (Gamma-interferon-induced monokine Q07325); MIP-1a (P10147); MIP-3a (P78556); MIP-1beta (P13236); MIP-1d (Q16663); NAG (N-acetyl-beta-D-glucosaminidase, P54802); Organic ion transporter (OCT2, 015244); Osteoprotegerin (O14788); P8 protein (O60356); Plasminogen activator inhibitor 1 (PAI-1, P05121); ProANP(1-98) (P01160); Protein phosphatase 1-beta (PPI-beta, P62140); Rab GDI-beta (P50395); Renal kallikrein (Q86U61); RT1.B-1 (alpha) chain of the integral membrane protein (Q5Y7A8); Soluble tumor necrosis factor receptor superfamily member 1A (sTNFR-I, P19438); Soluble tumor necrosis factor receptor superfamily member 1B (sTNFR-11, P20333); Tissue inhibitor of metalloproteinases 3 (TIMP-3, P35625); uPAR (Q03405) may be combined with the kidney injury marker assay result(s) of the present invention. 
     Other clinical indicia which may be combined with the kidney injury marker assay result(s) of the present invention includes demographic information (e.g., weight, sex, age, race), medical history (e.g., family history, type of surgery, pre-existing disease such as aneurism, congestive heart failure, preeclampsia, eclampsia, diabetes mellitus, hypertension, coronary artery disease, proteinuria, renal insufficiency, or sepsis, type of toxin exposure such as NSAIDs, cyclosporines, tacrolimus, aminoglycosides, foscarnet, ethylene glycol, hemoglobin, myoglobin, ifosfamide, heavy metals, methotrexate, radiopaque contrast agents, or streptozotocin), clinical variables (e.g., blood pressure, temperature, respiration rate), risk scores (APACHE score, PREDICT score, TIMI Risk Score for UA/NSTEMI, Framingham Risk Score), a urine total protein measurement, a glomerular filtration rate, an estimated glomerular filtration rate, a urine production rate, a serum or plasma creatinine concentration, a renal papillary antigen 1 (RPA1) measurement; a renal papillary antigen 2 (RPA2) measurement; a urine creatinine concentration, a fractional excretion of sodium, a urine sodium concentration, a urine creatinine to serum or plasma creatinine ratio, a urine specific gravity, a urine osmolality, a urine urea nitrogen to plasma urea nitrogen ratio, a plasma BUN to creatnine ratio, and/or a renal failure index calculated as urine sodium/(urine creatinine/plasma creatinine). Other measures of renal function which may be combined with the kidney injury marker assay result(s) are described hereinafter and in Harrison&#39;s Principles of Internal Medicine, 17 th  Ed., McGraw Hill, New York, pages 1741-1830, and Current Medical Diagnosis &amp; Treatment 2008, 47 th  Ed, McGraw Hill, New York, pages 785-815, each of which are hereby incorporated by reference in their entirety. 
     Combining assay results/clinical indicia in this manner can comprise the use of multivariate logistical regression, loglinear modeling, neural network analysis, n-of-m analysis, decision tree analysis, etc. This list is not meant to be limiting. 
     Diagnosis of Acute Renal Failure 
     As noted above, the terms “acute renal (or kidney) injury” and “acute renal (or kidney) failure” as used herein are defined in part in terms of changes in serum creatinine from a baseline value. Most definitions of ARF have common elements, including the use of serum creatinine and, often, urine output. Patients may present with renal dysfunction without an available baseline measure of renal function for use in this comparison. In such an event, one may estimate a baseline serum creatinine value by assuming the patient initially had a normal GFR. Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman&#39;s capsule per unit time. Glomerular filtration rate (GFR) can be calculated by measuring any chemical that has a steady level in the blood, and is freely filtered but neither reabsorbed nor secreted by the kidneys. GFR is typically expressed in units of ml/min: 
     
       
         
           
             GFR 
             = 
             
               
                 Urine 
                  
                 
                     
                 
                  
                 Concentration 
                 × 
                 Urine 
                  
                 
                     
                 
                  
                 Flow 
               
               
                 Plasma 
                  
                 
                     
                 
                  
                 Concentration 
               
             
           
         
       
     
     By normalizing the GFR to the body surface area, a GFR of approximately 75-100 ml/min per 1.73 m 2  can be assumed. The rate therefore measured is the quantity of the substance in the urine that originated from a calculable volume of blood. 
     There are several different techniques used to calculate or estimate the glomerular filtration rate (GFR or eGFR). In clinical practice, however, creatinine clearance is used to measure GFR. Creatinine is produced naturally by the body (creatinine is a metabolite of creatine, which is found in muscle). It is freely filtered by the glomerulus, but also actively secreted by the renal tubules in very small amounts such that creatinine clearance overestimates actual GFR by 10-20%. This margin of error is acceptable considering the ease with which creatinine clearance is measured. 
     Creatinine clearance (CCr) can be calculated if values for creatinine&#39;s urine concentration (U Cr ), urine flow rate (V), and creatinine&#39;s plasma concentration (P Cr ) are known. Since the product of urine concentration and urine flow rate yields creatinine&#39;s excretion rate, creatinine clearance is also said to be its excretion rate (U Cr ×V) divided by its plasma concentration. This is commonly represented mathematically as: 
     
       
         
           
             
               C 
               Cr 
             
             = 
             
               
                 
                   U 
                   Cr 
                 
                 × 
                 V 
               
               
                 P 
                 Cr 
               
             
           
         
       
     
     Commonly a 24 hour urine collection is undertaken, from empty-bladder one morning to the contents of the bladder the following morning, with a comparative blood test then taken: 
     
       
         
           
             
               C 
               Cr 
             
             = 
             
               
                 
                   U 
                   Cr 
                 
                 × 
                 24 
                  
                 
                   - 
                 
                  
                 hour 
                  
                 
                     
                 
                  
                 volume 
               
               
                 
                   P 
                   Cr 
                 
                 × 
                 24 
                 × 
                 60 
                  
                 
                     
                 
                  
                 mins 
               
             
           
         
       
     
     To allow comparison of results between people of different sizes, the CCr is often corrected for the body surface area (BSA) and expressed compared to the average sized man as ml/min/1.73 m2. While most adults have a BSA that approaches 1.7 (1.6-1.9), extremely obese or slim patients should have their CCr corrected for their actual BSA: 
     
       
         
           
             
               C 
               
                 Cr 
                  
                 
                   - 
                 
                  
                 corrected 
               
             
             = 
             
               
                 
                   C 
                   Cr 
                 
                 × 
                 1.73 
               
               BSA 
             
           
         
       
     
     The accuracy of a creatinine clearance measurement (even when collection is complete) is limited because as glomerular filtration rate (GFR) falls creatinine secretion is increased, and thus the rise in serum creatinine is less. Thus, creatinine excretion is much greater than the filtered load, resulting in a potentially large overestimation of the GFR (as much as a twofold difference). However, for clinical purposes it is important to determine whether renal function is stable or getting worse or better. This is often determined by monitoring serum creatinine alone. Like creatinine clearance, the serum creatinine will not be an accurate reflection of GFR in the non-steady-state condition of ARF. Nonetheless, the degree to which serum creatinine changes from baseline will reflect the change in GFR. Serum creatinine is readily and easily measured and it is specific for renal function. 
     For purposes of determining urine output on a Urine output on a mL/kg/hr basis, hourly urine collection and measurement is adequate. In the case where, for example, only a cumulative 24-h output was available and no patient weights are provided, minor modifications of the RIFLE urine output criteria have been described. For example, Bagshaw et al.,  Nephrol. Dial. Transplant.  23: 1203-1210, 2008, assumes an average patient weight of 70 kg, and patients are assigned a RIFLE classification based on the following: &lt;35 mL/h (Risk), &lt;21 mL/h (Injury) or &lt;4 mL/h (Failure). 
     Selecting a Treatment Regimen 
     Once a diagnosis is obtained, the clinician can readily select a treatment regimen that is compatible with the diagnosis, such as initiating renal replacement therapy, withdrawing delivery of compounds that are known to be damaging to the kidney, kidney transplantation, delaying or avoiding procedures that are known to be damaging to the kidney, modifying diuretic administration, initiating goal directed therapy, etc. The skilled artisan is aware of appropriate treatments for numerous diseases discussed in relation to the methods of diagnosis described herein. See, e.g., Merck Manual of Diagnosis and Therapy, 17th Ed. Merck Research Laboratories, Whitehouse Station, N.J., 1999. In addition, since the methods and compositions described herein provide prognostic information, the markers of the present invention may be used to monitor a course of treatment. For example, improved or worsened prognostic state may indicate that a particular treatment is or is not efficacious. 
     One skilled in the art readily appreciates that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The examples provided herein are representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. 
     Example 1 
     HA as a Diagnostic Marker of AKI 
     Urinary HA and plasma creatinine were measured in mice after administration of folic acid, a known nephrotoxin. Intraperitoneal injections of folic acid (FA, 300 mg/kg dissolved in NaHCO 3 ) was selected as a suitable dose to induce AKI (time=0 h) based on pilot studies which indicated that this dose was effective to cause increases in plasma creatinine levels indicative of AKI, but without FA leading to severe illness or death. Control animals received an equivalent volume of vehicle (NaHCO 3 ) i.p. Plasma creatinine and blood urea nitrogen (BUN) were measured to assess renal function using commercially available assays (creatinine kit from Diazyme (San Diego, Calif.), BUN kit from Sigma (St. Louis, Mo.)). Urinary HA levels were normalized by expressing the HA concentration per mg of urinary creatinine. 
     The results of this analysis are depicted in  FIG. 1 . As can be seen, normalized HA levels are reflective of creatinine levels indicative of AKI in this induced AKI model system. 
     Example 2 
     Use of HA as a Prognostic and Diagnostic Marker 
     Patients from the intensive care unit (ICU) were enrolled in the following study. Each patient was classified by kidney status as non-injury (O), risk of injury (R), injury (I), and failure (F) according to the maximum stage reached within 7 days of enrollment as determined by the RIFLE criteria. EDTA anti-coagulated blood samples (10 mL) and a urine samples (25-30 mL) were collected from each patient at enrollment, 4 (±0.5) and 8 (±1) hours after contrast administration (if applicable); at 12 (±1), 24 (±2), and 48 (±2) hours after enrollment, and thereafter daily up to day 7 to day 14 while the subject is hospitalized. HA was measured by standard immunoassay methods using commercially available assay reagents in the urine samples and the plasma component of the blood samples collected. 
     Two cohorts were defined as described in the introduction to each of the following tables. In the following tables, the time “prior max stage” represents the time at which a sample is collected, relative to the time a particular patient reaches the lowest disease stage as defined for that cohort, binned into three groups which are +/−12 hours. For example, “24 hr prior” which uses 0 vs R, I, F as the two cohorts would mean 24 hr (+/−12 hours) prior to reaching stage R (or I if no sample at R, or F if no sample at R or I). 
     A receiver operating characteristic (ROC) curve was generated for HA and the area under each ROC curve (AUC) was determined. Patients in Cohort 2 were also separated according to the reason for adjudication to cohort 2 as being based on serum creatinine measurements (sCr), being based on urine output (UO), or being based on either serum creatinine measurements or urine output. Using the same example discussed above (0 vs R, I, F), for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of urine output; for those patients adjudicated to stage R, I, or F on the basis of urine output alone, the stage 0 cohort may have included patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements; and for those patients adjudicated to stage R, I, or F on the basis of serum creatinine measurements or urine output, the stage 0 cohort contains only patients in stage 0 for both serum creatinine measurements and urine output. Also, in the data for patients adjudicated on the basis of serum creatinine measurements or urine output, the adjudication method which yielded the most severe RIFLE stage was used. 
     The ability to distinguish cohort 1 from Cohort 2 was determined using ROC analysis. SE is the standard error of the AUC, n is the number of sample or individual patients (“pts,” as indicated). Standard errors were calculated as described in Hanley, J. A., and McNeil, B. J., The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology (1982) 143: 29-36; p values were calculated with a two-tailed Z-test. An AUC&lt;0.5 is indicative of a negative going marker for the comparison, and an AUC&gt;0.5 is indicative of a positive going marker for the comparison. 
     Various HA threshold (or “cutoff”) concentrations were selected, and the associated sensitivity and specificity for distinguishing cohort 1 from cohort 2 were determined. OR is the odds ratio calculated for the particular cutoff concentration, and 95% CI is the confidence interval for the odds ratio. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Comparison of marker levels in urine samples collected from Cohort 
               
               
                 1 (patients that did not progress beyond RIFLE stage 0) and in urine samples collected 
               
               
                 from subjects at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 979 
                 1840 
                 979 
                 1280 
                 979 
                 1330 
               
               
                   
                 Average 
                 1290 
                 2010 
                 1290 
                 1870 
                 1290 
                 2030 
               
               
                   
                 Stdev 
                 1090 
                 1300 
                 1090 
                 1460 
                 1090 
                 1540 
               
               
                   
                 p (t-test) 
                   
                 2.3E−13 
                   
                 3.4E−8 
                   
                 3.0E−6 
               
               
                   
                 Min 
                 41.6 
                 151 
                 41.6 
                 77.8 
                 41.6 
                 126 
               
               
                   
                 Max 
                 6400 
                 5710 
                 6400 
                 6300 
                 6400 
                 5450 
               
               
                   
                 n (Samp) 
                 570 
                 189 
                 570 
                 170 
                 570 
                 58 
               
               
                   
                 n (Patient) 
                 259 
                 189 
                 259 
                 170 
                 259 
                 58 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 1280 
                 1600 
                 1280 
                 1550 
                 1280 
                 1150 
               
               
                   
                 Average 
                 1700 
                 1720 
                 1700 
                 1850 
                 1700 
                 1750 
               
               
                   
                 Stdev 
                 1350 
                 1120 
                 1350 
                 1290 
                 1350 
                 1440 
               
               
                   
                 p (t-test) 
                   
                 0.87 
                   
                 0.39 
                   
                 0.82 
               
               
                   
                 Min 
                 41.6 
                 151 
                 41.6 
                 77.8 
                 41.6 
                 152 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 5710 
                 6400 
                 5910 
               
               
                   
                 n (Samp) 
                 1322 
                 59 
                 1322 
                 60 
                 1322 
                 36 
               
               
                   
                 n (Patient) 
                 467 
                 59 
                 467 
                 60 
                 467 
                 36 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 1040 
                 2020 
                 1040 
                 1560 
                 1040 
                 1500 
               
               
                   
                 Average 
                 1370 
                 2230 
                 1370 
                 2090 
                 1370 
                 2130 
               
               
                   
                 Stdev 
                 1130 
                 1400 
                 1130 
                 1580 
                 1130 
                 1550 
               
               
                   
                 p (t-test) 
                   
                 4.7E−16 
                   
                 1.5E−10 
                   
                 6.0E−6 
               
               
                   
                 Min 
                 41.6 
                 168 
                 41.6 
                 91.1 
                 41.6 
                 126 
               
               
                   
                 Max 
                 5540 
                 6400 
                 5540 
                 6390 
                 5540 
                 6190 
               
               
                   
                 n (Samp) 
                 587 
                 173 
                 587 
                 161 
                 587 
                 54 
               
               
                   
                 n (Patient) 
                 223 
                 173 
                 223 
                 161 
                 223 
                 54 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.69 
                 0.54 
                 0.71 
                 0.62 
                 0.56 
                 0.64 
                 0.63 
                 0.51 
                 0.64 
               
               
                 SE 
                 0.024 
                 0.039 
                 0.024 
                 0.025 
                 0.039 
                 0.026 
                 0.041 
                 0.049 
                 0.042 
               
               
                 p 
                 4.0E−15 
                 0.26 
                 0 
                 1.9E−6 
                 0.16 
                 8.9E−8 
                 9.4E−4 
                 0.88 
                 5.9E−4 
               
               
                 nCohort 1 
                 570 
                 1322 
                 587 
                 570 
                 1322 
                 587 
                 570 
                 1322 
                 587 
               
               
                 nCohort 2 
                 189 
                 59 
                 173 
                 170 
                 60 
                 161 
                 58 
                 36 
                 54 
               
               
                 Cutoff 1 
                 1180 
                 1040 
                 1360 
                 886 
                 1100 
                 964 
                 854 
                 849 
                 976 
               
               
                 Sens 1 
                 70% 
                 71% 
                 71% 
                 70% 
                 70% 
                 70% 
                 71% 
                 72% 
                 70% 
               
               
                 Spec 1 
                 58% 
                 40% 
                 64% 
                 45% 
                 42% 
                 46% 
                 43% 
                 32% 
                 47% 
               
               
                 Cutoff 2 
                 893 
                 640 
                 1020 
                 690 
                 770 
                 741 
                 719 
                 648 
                 776 
               
               
                 Sens 2 
                 80% 
                 81% 
                 80% 
                 80% 
                 80% 
                 80% 
                 81% 
                 81% 
                 81% 
               
               
                 Spec 2 
                 46% 
                 22% 
                 49% 
                 35% 
                 29% 
                 35% 
                 37% 
                 22% 
                 38% 
               
               
                 Cutoff 3 
                 451 
                 358 
                 583 
                 392 
                 389 
                 465 
                 437 
                 477 
                 437 
               
               
                 Sens 3 
                 90% 
                 92% 
                 90% 
                 90% 
                 90% 
                 90% 
                 91% 
                 92% 
                 91% 
               
               
                 Spec 3 
                 19% 
                  9% 
                 25% 
                 16% 
                 10% 
                 18% 
                 19% 
                 15% 
                 17% 
               
               
                 Cutoff 4 
                 1480 
                 2010 
                 1600 
                 1480 
                 2010 
                 1600 
                 1480 
                 2010 
                 1600 
               
               
                 Sens 4 
                 61% 
                 37% 
                 65% 
                 46% 
                 37% 
                 49% 
                 47% 
                 36% 
                 48% 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 1820 
                 2610 
                 2010 
                 1820 
                 2610 
                 2010 
                 1820 
                 2610 
                 2010 
               
               
                 Sens 5 
                 52% 
                 19% 
                 50% 
                 42% 
                 20% 
                 42% 
                 45% 
                 19% 
                 46% 
               
               
                 Spec 5 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 2660 
                 3790 
                 2890 
                 2660 
                 3790 
                 2890 
                 2660 
                 3790 
                 2890 
               
               
                 Sens 6 
                 25% 
                  2% 
                 24% 
                 25% 
                  8% 
                 27% 
                 34% 
                 11% 
                 33% 
               
               
                 Spec 6 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 1.1 
                 0.66 
                 1.3 
                 1.6 
                 1.6 
                 2.6 
                 1.8 
                 1.1 
                 1.3 
               
               
                 p Value 
                 0.79 
                 0.37 
                 0.43 
                 0.10 
                 0.24 
                 0.0013 
                 0.19 
                 0.82 
                 0.63 
               
               
                 95% CI of 
                 0.61 
                 0.27 
                 0.69 
                 0.91 
                 0.73 
                 1.4 
                 0.74 
                 0.45 
                 0.49 
               
               
                 OR Quart 2 
                 1.9 
                 1.6 
                 2.4 
                 2.7 
                 3.6 
                 4.6 
                 4.5 
                 2.8 
                 3.3 
               
               
                 OR Quart 3 
                 1.9 
                 1.8 
                 2.7 
                 1.4 
                 1.6 
                 1.5 
                 1.3 
                 0.89 
                 1.4 
               
               
                 p Value 
                 0.015 
                 0.11 
                 5.9E−4  
                 0.21 
                 0.23 
                 0.22 
                 0.63 
                 0.81 
                 0.48 
               
               
                 95% CI of 
                 1.1 
                 0.87 
                 1.5 
                 0.82 
                 0.73 
                 0.80 
                 0.49 
                 0.34 
                 0.55 
               
               
                 OR Quart 3 
                 3.2 
                 3.7 
                 4.8 
                 2.5 
                 3.6 
                 2.7 
                 3.3 
                 2.3 
                 3.6 
               
               
                 OR Quart 4 
                 5.1 
                 1.5 
                 6.5 
                 3.8 
                 1.8 
                 4.9 
                 3.7 
                 1.00 
                 3.5 
               
               
                 p Value 
                 1.6E−10 
                 0.27 
                 2.0E−11 
                 2.7E−7 
                 0.13 
                 1.7E−8 
                 0.0019 
                 0.99 
                 0.0031 
               
               
                 95% CI of 
                 3.1 
                 0.72 
                 3.7 
                 2.3 
                 0.84 
                 2.8 
                 1.6 
                 0.39 
                 1.5 
               
               
                 OR Quart 4 
                 8.3 
                 3.2 
                 11 
                 6.3 
                 4.0 
                 8.5 
                 8.4 
                 2.5 
                 8.0 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Comparison of marker levels in urine samples collected from Cohort 
               
               
                 1 (patients that did not progress beyond RIFLE stage 0 or R) and in urine samples 
               
               
                 collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 1180 
                 2190 
                 1180 
                 2050 
                 1180 
                 1880 
               
               
                   
                 Average 
                 1500 
                 2440 
                 1500 
                 2450 
                 1500 
                 2100 
               
               
                   
                 Stdev 
                 1190 
                 1460 
                 1190 
                 1650 
                 1190 
                 1620 
               
               
                   
                 p (t-test) 
                   
                 1.3E−13 
                   
                 7.7E−14 
                   
                 2.0E−4 
               
               
                   
                 Min 
                 41.6 
                 89.4 
                 41.6 
                 110 
                 41.6 
                 81.2 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6190 
               
               
                   
                 n (Samp) 
                 1183 
                 102 
                 1183 
                 106 
                 1183 
                 61 
               
               
                   
                 n (Patient) 
                 444 
                 102 
                 444 
                 106 
                 444 
                 61 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 1330 
                 1760 
                 1330 
                 2010 
                 1330 
                 1550 
               
               
                   
                 Average 
                 1740 
                 2060 
                 1740 
                 2430 
                 1740 
                 1970 
               
               
                   
                 Stdev 
                 1380 
                 1260 
                 1380 
                 1470 
                 1380 
                 1530 
               
               
                   
                 p (t-test) 
                   
                 0.28 
                   
                 0.0085 
                   
                 0.42 
               
               
                   
                 Min 
                 41.6 
                 404 
                 41.6 
                 340 
                 41.6 
                 324 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
               
               
                   
                 n (Samp) 
                 1617 
                 22 
                 1617 
                 29 
                 1617 
                 25 
               
               
                   
                 n (Patient) 
                 556 
                 22 
                 556 
                 29 
                 556 
                 25 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 1220 
                 2330 
                 1220 
                 2180 
                 1220 
                 1950 
               
               
                   
                 Average 
                 1550 
                 2600 
                 1550 
                 2510 
                 1550 
                 2290 
               
               
                   
                 Stdev 
                 1200 
                 1530 
                 1200 
                 1700 
                 1200 
                 1700 
               
               
                   
                 p (t-test) 
                   
                 5.8E−15 
                   
                 5.4E−13 
                   
                 2.3E−5 
               
               
                   
                 Min 
                 41.6 
                 89.4 
                 41.6 
                 110 
                 41.6 
                 81.2 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6190 
               
               
                   
                 n (Samp) 
                 1118 
                 93 
                 1118 
                 97 
                 1118 
                 52 
               
               
                   
                 n (Patient) 
                 382 
                 93 
                 382 
                 97 
                 382 
                 52 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.71 
                 0.62 
                 0.71 
                 0.68 
                 0.66 
                 0.67 
                 0.60 
                 0.55 
                 0.62 
               
               
                 SE 
                 0.030 
                 0.064 
                 0.031 
                 0.030 
                 0.056 
                 0.031 
                 0.039 
                 0.060 
                 0.042 
               
               
                 p 
                 2.0E−12 
                 0.069 
                 3.6E−12 
                 1.5E−9 
                 0.0033 
                 2.0E−8 
                 0.012 
                 0.36 
                 0.0051 
               
               
                 nCohort 1 
                 1183 
                 1617 
                 1118 
                 1183 
                 1617 
                 1118 
                 1183 
                 1617 
                 1118 
               
               
                 nCohort 2 
                 102 
                 22 
                 93 
                 106 
                 29 
                 97 
                 61 
                 25 
                 52 
               
               
                 Cutoff 1 
                 1590 
                 1340 
                 1660 
                 1330 
                 1710 
                 1400 
                 886 
                 1100 
                 957 
               
               
                 Sens 1 
                 71% 
                 73% 
                 71% 
                 71% 
                 72% 
                 70% 
                 70% 
                 72% 
                 71% 
               
               
                 Spec 1 
                 65% 
                 50% 
                 65% 
                 57% 
                 61% 
                 57% 
                 37% 
                 41% 
                 38% 
               
               
                 Cutoff 2 
                 1160 
                 1070 
                 1190 
                 923 
                 1150 
                 819 
                 582 
                 770 
                 648 
               
               
                 Sens 2 
                 80% 
                 82% 
                 81% 
                 80% 
                 83% 
                 80% 
                 80% 
                 80% 
                 81% 
               
               
                 Spec 2 
                 49% 
                 40% 
                 49% 
                 39% 
                 42% 
                 32% 
                 22% 
                 28% 
                 23% 
               
               
                 Cutoff 3 
                 671 
                 1020 
                 671 
                 515 
                 641 
                 513 
                 469 
                 537 
                 470 
               
               
                 Sens 3 
                 90% 
                 91% 
                 90% 
                 91% 
                 93% 
                 91% 
                 90% 
                 92% 
                 90% 
               
               
                 Spec 3 
                 26% 
                 38% 
                 25% 
                 18% 
                 21% 
                 17% 
                 16% 
                 17% 
                 15% 
               
               
                 Cutoff 4 
                 1770 
                 2050 
                 1850 
                 1770 
                 2050 
                 1850 
                 1770 
                 2050 
                 1850 
               
               
                 Sens 4 
                 62% 
                 41% 
                 66% 
                 58% 
                 48% 
                 59% 
                 51% 
                 36% 
                 54% 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 2160 
                 2700 
                 2280 
                 2160 
                 2700 
                 2280 
                 2160 
                 2700 
                 2280 
               
               
                 Sens 5 
                 51% 
                 18% 
                 51% 
                 48% 
                 31% 
                 47% 
                 39% 
                 16% 
                 40% 
               
               
                 Spec 5 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 3280 
                 3830 
                 3390 
                 3280 
                 3830 
                 3390 
                 3280 
                 3830 
                 3390 
               
               
                 Sens 6 
                 24% 
                  5% 
                 27% 
                 24% 
                 14% 
                 26% 
                 26% 
                 12% 
                 29% 
               
               
                 Spec 6 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 1.3 
                 5.0 
                 1.2 
                 1.1 
                 1.00 
                 1.2 
                 0.59 
                 1.2 
                 0.49 
               
               
                 p Value 
                 0.53 
                 0.14 
                 0.67 
                 0.85 
                 1.00 
                 0.71 
                 0.22 
                 0.76 
                 0.16 
               
               
                 95% CI of 
                 0.57 
                 0.59 
                 0.51 
                 0.51 
                 0.20 
                 0.54 
                 0.25 
                 0.36 
                 0.18 
               
               
                 OR Quart 2 
                 3.0 
                 43 
                 2.8 
                 2.3 
                 5.0 
                 2.5 
                 1.4 
                 4.0 
                 1.3 
               
               
                 OR Quart 3 
                 2.5 
                 8.1 
                 1.8 
                 1.8 
                 3.7 
                 1.5 
                 0.59 
                 1.6 
                 0.91 
               
               
                 p Value 
                 0.017 
                 0.049 
                 0.13 
                 0.098 
                 0.044 
                 0.28 
                 0.22 
                 0.41 
                 0.83 
               
               
                 95% CI of 
                 1.2 
                 1.0 
                 0.84 
                 0.90 
                 1.0 
                 0.72 
                 0.25 
                 0.52 
                 0.40 
               
               
                 OR Quart 3 
                 5.3 
                 65 
                 4.1 
                 3.5 
                 14 
                 3.1 
                 1.4 
                 5.0 
                 2.1 
               
               
                 OR Quart 4 
                 6.4 
                 8.1 
                 6.2 
                 4.3 
                 4.1 
                 4.4 
                 2.0 
                 1.2 
                 2.0 
               
               
                 p Value 
                 1.5E−7  
                 0.049 
                 2.9E−7  
                 2.7E−6 
                 0.030 
                 4.6E−6 
                 0.043 
                 0.76 
                 0.061 
               
               
                 95% CI of 
                 3.2 
                 1.0 
                 3.1 
                 2.3 
                 1.1 
                 2.3 
                 1.0 
                 0.36 
                 0.97 
               
               
                 OR Quart 4 
                 13 
                 65 
                 12 
                 8.0 
                 15 
                 8.3 
                 3.7 
                 4.0 
                 4.1 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Comparison of marker levels in urine samples collected within 12 
               
               
                 hours of reaching stage R from Cohort 1 (patients that reached, but did 
               
               
                 not progress beyond, RIFLE stage R) and from Cohort 2 (patients that 
               
               
                 reached RIFLE stage I or F). 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
               
               
                   
                 1 
                 2 
                 1 
                 2 
                 1 
                 2 
               
               
                   
               
               
                 Median 
                 1680 
                 2050 
                 1600 
                 2430 
                 1850 
                 1870 
               
               
                 Average 
                 1830 
                 2300 
                 1950 
                 2470 
                 1950 
                 2220 
               
               
                 Stdev 
                 1160 
                 1540 
                 1410 
                 1360 
                 1130 
                 1550 
               
               
                 p (t-test) 
                   
                 0.0071 
                   
                 0.15 
                   
                 0.16 
               
               
                 Min 
                 151 
                 183 
                 151 
                 183 
                 168 
                 190 
               
               
                 Max 
                 5180 
                 6350 
                 6400 
                 5250 
                 5180 
                 6400 
               
               
                 n (Samp) 
                 169 
                 84 
                 65 
                 20 
                 142 
                 64 
               
               
                 n (Patient) 
                 169 
                 84 
                 65 
                 20 
                 142 
                 64 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 At Enrollment 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
                   
               
               
                   
                 AUC 
                 0.58 
                 0.62 
                 0.53 
               
               
                   
                 SE 
                 0.039 
                 0.075 
                 0.044 
               
               
                   
                 p 
                 0.033 
                 0.097 
                 0.55 
               
               
                   
                 nCohort 1 
                 169 
                 65 
                 142 
               
               
                   
                 nCohort 2 
                 84 
                 20 
                 64 
               
               
                   
                 Cutoff 1 
                 1270 
                 1940 
                 1270 
               
               
                   
                 Sens 1 
                 70% 
                 70% 
                 70% 
               
               
                   
                 Spec 1 
                 36% 
                 60% 
                 31% 
               
               
                   
                 Cutoff 2 
                 945 
                 1400 
                 1000 
               
               
                   
                 Sens 2 
                 81% 
                 80% 
                 81% 
               
               
                   
                 Spec 2 
                 23% 
                 38% 
                 22% 
               
               
                   
                 Cutoff 3 
                 550 
                 842 
                 582 
               
               
                   
                 Sens 3 
                 90% 
                 90% 
                 91% 
               
               
                   
                 Spec 3 
                 13% 
                 26% 
                 10% 
               
               
                   
                 Cutoff 4 
                 2150 
                 2560 
                 2280 
               
               
                   
                 Sens 4 
                 48% 
                 50% 
                 34% 
               
               
                   
                 Spec 4 
                 70% 
                 71% 
                 70% 
               
               
                   
                 Cutoff 5 
                 2700 
                 2940 
                 2770 
               
               
                   
                 Sens 5 
                 32% 
                 35% 
                 23% 
               
               
                   
                 Spec 5 
                 80% 
                 80% 
                 80% 
               
               
                   
                 Cutoff 6 
                 3530 
                 3790 
                 3470 
               
               
                   
                 Sens 6 
                 18% 
                 15% 
                 17% 
               
               
                   
                 Spec 6 
                 91% 
                 91% 
                 90% 
               
               
                   
                 OR Quart 2 
                 0.93 
                 0.63 
                 1.4 
               
               
                   
                 p Value 
                 0.84 
                 0.64 
                 0.43 
               
               
                   
                 95% CI of 
                 0.43 
                 0.094 
                 0.60 
               
               
                   
                 OR Quart 2 
                 2.0 
                 4.2 
                 3.2 
               
               
                   
                 OR Quart 3 
                 1.0 
                 3.7 
                 1.1 
               
               
                   
                 p Value 
                 1.0 
                 0.089 
                 0.83 
               
               
                   
                 95% CI of 
                 0.47 
                 0.82 
                 0.47 
               
               
                   
                 OR Quart 3 
                 2.1 
                 17 
                 2.6 
               
               
                   
                 OR Quart 4 
                 1.8 
                 2.8 
                 1.3 
               
               
                   
                 p Value 
                 0.11 
                 0.18 
                 0.56 
               
               
                   
                 95% CI of 
                 0.87 
                 0.61 
                 0.55 
               
               
                   
                 OR Quart 4 
                 3.7 
                 13 
                 3.0 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Comparison of the maximum marker levels in urine samples 
               
               
                 collected from Cohort 1 (patients that did not progress beyond RIFLE stage 0) and the 
               
               
                 maximum values in urine samples collected from subjects between enrollment and 0, 24 
               
               
                 hours, and 48 hours prior to reaching stage F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 1250 
                 3410 
                 1250 
                 3300 
                 1250 
                 3210 
               
               
                   
                 Average 
                 1570 
                 3520 
                 1570 
                 3470 
                 1570 
                 3050 
               
               
                   
                 Stdev 
                 1190 
                 1570 
                 1190 
                 1580 
                 1190 
                 1230 
               
               
                   
                 p (t-test) 
                   
                 3.9E−19 
                   
                 5.2E−18 
                   
                 1.6E−8 
               
               
                   
                 Min 
                 69.2 
                 565 
                 69.2 
                 565 
                 69.2 
                 1020 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6190 
               
               
                   
                 n (Samp) 
                 259 
                 44 
                 259 
                 43 
                 259 
                 24 
               
               
                   
                 n (Patient) 
                 259 
                 44 
                 259 
                 43 
                 259 
                 24 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 1760 
                 3240 
                 1760 
                 3170 
                 1760 
                 3110 
               
               
                   
                 Average 
                 2100 
                 3070 
                 2100 
                 2930 
                 2100 
                 2860 
               
               
                   
                 Stdev 
                 1470 
                 1530 
                 1470 
                 1380 
                 1470 
                 945 
               
               
                   
                 p (t-test) 
                   
                 0.0033 
                   
                 0.012 
                   
                 0.056 
               
               
                   
                 Min 
                 69.2 
                 565 
                 69.2 
                 565 
                 69.2 
                 1330 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 5080 
                 6400 
                 4360 
               
               
                   
                 n (Samp) 
                 467 
                 21 
                 467 
                 21 
                 467 
                 14 
               
               
                   
                 n (Patient) 
                 467 
                 21 
                 467 
                 21 
                 467 
                 14 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 1400 
                 3720 
                 1400 
                 3600 
                 1400 
                 3130 
               
               
                   
                 Average 
                 1790 
                 3850 
                 1790 
                 3800 
                 1790 
                 3090 
               
               
                   
                 Stdev 
                 1250 
                 1590 
                 1250 
                 1610 
                 1250 
                 1400 
               
               
                   
                 p (t-test) 
                   
                 3.0E−15 
                   
                 2.8E−14 
                   
                 3.7E−5 
               
               
                   
                 Min 
                 113 
                 687 
                 113 
                 687 
                 113 
                 1020 
               
               
                   
                 Max 
                 5540 
                 6400 
                 5540 
                 6400 
                 5540 
                 6190 
               
               
                   
                 n (Samp) 
                 223 
                 32 
                 223 
                 31 
                 223 
                 18 
               
               
                   
                 n (Patient) 
                 223 
                 32 
                 223 
                 31 
                 223 
                 18 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.84 
                 0.69 
                 0.85 
                 0.83 
                 0.68 
                 0.84 
                 0.83 
                 0.71 
                 0.78 
               
               
                 SE 
                 0.039 
                 0.065 
                 0.044 
                 0.040 
                 0.066 
                 0.045 
                 0.053 
                 0.079 
                 0.066 
               
               
                 p 
                 0 
                 0.0035 
                 5.6E−15 
                 0 
                 0.0064 
                 7.5E−14 
                 3.5E−10 
                 0.0095 
                 2.3E−5 
               
               
                 nCohort 1 
                 259 
                 467 
                 223 
                 259 
                 467 
                 223 
                 259 
                 467 
                 223 
               
               
                 nCohort 2 
                 44 
                 21 
                 32 
                 43 
                 21 
                 31 
                 24 
                 14 
                 18 
               
               
                 Cutoff 1 
                 2720 
                 2210 
                 2910 
                 2710 
                 2210 
                 2800 
                 2200 
                 2210 
                 2170 
               
               
                 Sens 1 
                 70% 
                 71% 
                 72% 
                 72% 
                 71% 
                 71% 
                 71% 
                 71% 
                 72% 
               
               
                 Spec 1 
                 85% 
                 65% 
                 84% 
                 85% 
                 65% 
                 83% 
                 79% 
                 65% 
                 73% 
               
               
                 Cutoff 2 
                 2170 
                 1810 
                 2470 
                 2170 
                 1810 
                 2470 
                 1810 
                 1810 
                 1660 
               
               
                 Sens 2 
                 82% 
                 81% 
                 81% 
                 81% 
                 81% 
                 81% 
                 83% 
                 86% 
                 83% 
               
               
                 Spec 2 
                 79% 
                 52% 
                 77% 
                 79% 
                 52% 
                 77% 
                 70% 
                 52% 
                 58% 
               
               
                 Cutoff 3 
                 1060 
                 1060 
                 1810 
                 1060 
                 1060 
                 1810 
                 1590 
                 1590 
                 1320 
               
               
                 Sens 3 
                 91% 
                 90% 
                 91% 
                 91% 
                 90% 
                 90% 
                 92% 
                 93% 
                 94% 
               
               
                 Spec 3 
                 42% 
                 28% 
                 63% 
                 42% 
                 28% 
                 63% 
                 63% 
                 45% 
                 48% 
               
               
                 Cutoff 4 
                 1860 
                 2450 
                 2120 
                 1860 
                 2450 
                 2120 
                 1860 
                 2450 
                 2120 
               
               
                 Sens 4 
                 84% 
                 67% 
                 88% 
                 84% 
                 67% 
                 87% 
                 79% 
                 64% 
                 72% 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 2270 
                 3280 
                 2630 
                 2270 
                 3280 
                 2630 
                 2270 
                 3280 
                 2630 
               
               
                 Sens 5 
                 77% 
                 43% 
                 78% 
                 77% 
                 38% 
                 77% 
                 67% 
                 36% 
                 67% 
               
               
                 Spec 5 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 3260 
                 4350 
                 3660 
                 3260 
                 4350 
                 3660 
                 3260 
                 4350 
                 3660 
               
               
                 Sens 6 
                 57% 
                 19% 
                 50% 
                 53% 
                 19% 
                 48% 
                 46% 
                  7% 
                 22% 
               
               
                 Spec 6 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 2.0 
                 1.0 
                 2.0 
                 0.99 
                 1.0 
                 2.0 
                 &gt;1.0 
                 &gt;2.0 
                 &gt;2.1 
               
               
                 p Value 
                 0.42 
                 1.0 
                 0.58 
                 0.99 
                 1.0 
                 0.58 
                 &lt;1.0 
                 &lt;0.56 
                 &lt;0.56 
               
               
                 95% CI of 
                 0.36 
                 0.14 
                 0.18 
                 0.19 
                 0.14 
                 0.18 
                 &gt;0.061 
                 &gt;0.18 
                 &gt;0.18 
               
               
                 OR Quart 2 
                 11 
                 7.2 
                 23 
                 5.0 
                 7.2 
                 23 
                 na 
                 na 
                 na 
               
               
                 OR Quart 3 
                 3.1 
                 2.6 
                 5.3 
                 2.1 
                 2.6 
                 4.2 
                 &gt;7.7 
                 &gt;4.1 
                 &gt;4.3 
               
               
                 p Value 
                 0.17 
                 0.27 
                 0.14 
                 0.31 
                 0.27 
                 0.20 
                 &lt;0.060 
                 &lt;0.21 
                 &lt;0.20 
               
               
                 95% CI of 
                 0.61 
                 0.49 
                 0.60 
                 0.50 
                 0.49 
                 0.46 
                 &gt;0.92 
                 &gt;0.46 
                 &gt;0.46 
               
               
                 OR Quart 3 
                 16 
                 13 
                 46 
                 8.7 
                 13 
                 39 
                 na 
                 na 
                 na 
               
               
                 OR Quart 4 
                 27 
                 6.5 
                 37 
                 17 
                 6.5 
                 37 
                 &gt;20 
                 &gt;8.5 
                 &gt;15 
               
               
                 p Value 
                 1.4E−5 
                 0.015 
                 5.1E−4  
                 9.6E−6 
                 0.015 
                 5.1E−4  
                 &lt;0.0040 
                 &lt;0.045 
                 &lt;0.011 
               
               
                 95% CI of 
                 6.1 
                 1.4 
                 4.8 
                 4.8 
                 1.4 
                 4.8 
                 &gt;2.6 
                 &gt;1.0 
                 &gt;1.8 
               
               
                 OR Quart 4 
                 120 
                 30 
                 290 
                 57 
                 30 
                 290 
                 na 
                 na 
                 na 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Comparison of marker levels in EDTA samples collected from 
               
               
                 Cohort 1 (patients that did not progress beyond RIFLE stage 0) and in EDTA samples 
               
               
                 collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage R, I or F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 284 
                 335 
                 284 
                 331 
                 284 
                 428 
               
               
                   
                 Average 
                 501 
                 570 
                 501 
                 708 
                 501 
                 930 
               
               
                   
                 Stdev 
                 627 
                 641 
                 627 
                 839 
                 627 
                 999 
               
               
                   
                 p (t-test) 
                   
                 0.43 
                   
                 0.053 
                   
                 0.021 
               
               
                   
                 Min 
                 86.8 
                 74.7 
                 86.8 
                 63.6 
                 86.8 
                 132 
               
               
                   
                 Max 
                 3370 
                 3170 
                 3370 
                 3200 
                 3370 
                 3200 
               
               
                   
                 n (Samp) 
                 162 
                 77 
                 162 
                 56 
                 162 
                 14 
               
               
                   
                 n (Patient) 
                 90 
                 77 
                 90 
                 56 
                 90 
                 14 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 290 
                 350 
                 290 
                 573 
                 290 
                 309 
               
               
                   
                 Average 
                 619 
                 505 
                 619 
                 540 
                 619 
                 374 
               
               
                   
                 Stdev 
                 764 
                 488 
                 764 
                 251 
                 764 
                 269 
               
               
                   
                 p (t-test) 
                   
                 0.50 
                   
                 0.71 
                   
                 0.43 
               
               
                   
                 Min 
                 48.0 
                 105 
                 48.0 
                 183 
                 48.0 
                 112 
               
               
                   
                 Max 
                 3370 
                 2060 
                 3370 
                 1020 
                 3370 
                 832 
               
               
                   
                 n (Samp) 
                 378 
                 21 
                 378 
                 13 
                 378 
                 6 
               
               
                   
                 n (Patient) 
                 178 
                 21 
                 178 
                 13 
                 178 
                 6 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 323 
                 384 
                 323 
                 330 
                 323 
                 499 
               
               
                   
                 Average 
                 544 
                 626 
                 544 
                 724 
                 544 
                 1070 
               
               
                   
                 Stdev 
                 603 
                 688 
                 603 
                 863 
                 603 
                 1080 
               
               
                   
                 p (t-test) 
                   
                 0.36 
                   
                 0.075 
                   
                 0.0012 
               
               
                   
                 Min 
                 86.8 
                 74.7 
                 86.8 
                 63.6 
                 86.8 
                 132 
               
               
                   
                 Max 
                 3370 
                 3170 
                 3370 
                 3200 
                 3370 
                 3200 
               
               
                   
                 n (Samp) 
                 187 
                 66 
                 187 
                 59 
                 187 
                 18 
               
               
                   
                 n (Patient) 
                 94 
                 66 
                 94 
                 59 
                 94 
                 18 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.56 
                 0.52 
                 0.54 
                 0.57 
                 0.65 
                 0.53 
                 0.65 
                 0.45 
                 0.65 
               
               
                 SE 
                 0.040 
                 0.066 
                 0.042 
                 0.045 
                 0.084 
                 0.044 
                 0.082 
                 0.12 
                 0.073 
               
               
                 p 
                 0.16 
                 0.73 
                 0.33 
                 0.12 
                 0.077 
                 0.56 
                 0.070 
                 0.70 
                 0.039 
               
               
                 nCohort 1 
                 162 
                 378 
                 187 
                 162 
                 378 
                 187 
                 162 
                 378 
                 187 
               
               
                 nCohort 2 
                 77 
                 21 
                 66 
                 56 
                 13 
                 59 
                 14 
                 6 
                 18 
               
               
                 Cutoff 1 
                 246 
                 280 
                 248 
                 217 
                 326 
                 217 
                 317 
                 156 
                 317 
               
               
                 Sens 1 
                 70% 
                 71% 
                 71% 
                 71% 
                 77% 
                 71% 
                 71% 
                 83% 
                 72% 
               
               
                 Spec 1 
                 40% 
                 47% 
                 36% 
                 33% 
                 55% 
                 28% 
                 55% 
                 15% 
                 49% 
               
               
                 Cutoff 2 
                 198 
                 194 
                 217 
                 190 
                 318 
                 190 
                 182 
                 156 
                 212 
               
               
                 Sens 2 
                 81% 
                 81% 
                 80% 
                 80% 
                 85% 
                 81% 
                 86% 
                 83% 
                 83% 
               
               
                 Spec 2 
                 28% 
                 25% 
                 28% 
                 27% 
                 53% 
                 22% 
                 26% 
                 15% 
                 27% 
               
               
                 Cutoff 3 
                 124 
                 124 
                 141 
                 150 
                 232 
                 141 
                 168 
                 111 
                 168 
               
               
                 Sens 3 
                 91% 
                 90% 
                 91% 
                 91% 
                 92% 
                 92% 
                 93% 
                 100%  
                 94% 
               
               
                 Spec 3 
                 10% 
                  8% 
                 12% 
                 17% 
                 35% 
                 12% 
                 23% 
                  4% 
                 19% 
               
               
                 Cutoff 4 
                 409 
                 491 
                 501 
                 409 
                 491 
                 501 
                 409 
                 491 
                 501 
               
               
                 Sens 4 
                 40% 
                 33% 
                 29% 
                 48% 
                 54% 
                 36% 
                 50% 
                 33% 
                 50% 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 578 
                 833 
                 751 
                 578 
                 833 
                 751 
                 578 
                 833 
                 751 
               
               
                 Sens 5 
                 25% 
                 14% 
                 26% 
                 32% 
                 15% 
                 24% 
                 43% 
                  0% 
                 44% 
               
               
                 Spec 5 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 1030 
                 1820 
                 1320 
                 1030 
                 1820 
                 1320 
                 1030 
                 1820 
                 1320 
               
               
                 Sens 6 
                 12% 
                  5% 
                 12% 
                 20% 
                  0% 
                 20% 
                 29% 
                  0% 
                 28% 
               
               
                 Spec 6 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 1.4 
                 0.73 
                 1.4 
                 1.5 
                 0.99 
                 0.89 
                 1.0 
                 2.0 
                 1.0 
               
               
                 p Value 
                 0.45 
                 0.69 
                 0.40 
                 0.40 
                 0.99 
                 0.79 
                 1.0 
                 0.57 
                 1.0 
               
               
                 95% CI of 
                 0.61 
                 0.16 
                 0.62 
                 0.60 
                 0.061 
                 0.39 
                 0.13 
                 0.18 
                 0.19 
               
               
                 OR Quart 2 
                 3.0 
                 3.4 
                 3.2 
                 3.6 
                 16 
                 2.1 
                 7.4 
                 23 
                 5.2 
               
               
                 OR Quart 3 
                 1.6 
                 2.3 
                 1.5 
                 1.0 
                 5.2 
                 0.83 
                 2.1 
                 1.0 
                 1.4 
               
               
                 p Value 
                 0.26 
                 0.17 
                 0.30 
                 1.0 
                 0.14 
                 0.67 
                 0.41 
                 1.0 
                 0.70 
               
               
                 95% CI of 
                 0.72 
                 0.70 
                 0.68 
                 0.39 
                 0.59 
                 0.36 
                 0.36 
                 0.062 
                 0.29 
               
               
                 OR Quart 3 
                 3.5 
                 7.9 
                 3.5 
                 2.6 
                 45 
                 1.9 
                 12 
                 16 
                 6.4 
               
               
                 OR Quart 4 
                 1.7 
                 1.2 
                 1.5 
                 2.1 
                 6.3 
                 1.2 
                 3.3 
                 2.0 
                 2.9 
               
               
                 p Value 
                 0.19 
                 0.75 
                 0.33 
                 0.10 
                 0.092 
                 0.72 
                 0.16 
                 0.57 
                 0.13 
               
               
                 95% CI of 
                 0.77 
                 0.33 
                 0.66 
                 0.87 
                 0.74 
                 0.52 
                 0.63 
                 0.18 
                 0.73 
               
               
                 OR Quart 4 
                 3.7 
                 4.8 
                 3.4 
                 4.9 
                 53 
                 2.6 
                 17 
                 23 
                 12 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Comparison of marker levels in EDTA samples collected from 
               
               
                 Cohort 1 (patients that did not progress beyond RIFLE stage 0 or R) and in EDTA 
               
               
                 samples collected from subjects at 0, 24 hours, and 48 hours prior to reaching stage I or F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 317 
                 318 
                 317 
                 318 
                 317 
                 524 
               
               
                   
                 Average 
                 581 
                 651 
                 581 
                 739 
                 581 
                 729 
               
               
                   
                 Stdev 
                 680 
                 806 
                 680 
                 882 
                 680 
                 794 
               
               
                   
                 p (t-test) 
                   
                 0.61 
                   
                 0.19 
                   
                 0.36 
               
               
                   
                 Min 
                 74.7 
                 113 
                 74.7 
                 48.0 
                 74.7 
                 112 
               
               
                   
                 Max 
                 3370 
                 2880 
                 3370 
                 3200 
                 3370 
                 2810 
               
               
                   
                 n (Samp) 
                 357 
                 28 
                 357 
                 37 
                 357 
                 19 
               
               
                   
                 n (Patient) 
                 179 
                 28 
                 179 
                 37 
                 179 
                 19 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 nd 
                 nd 
                 nd 
                 nd 
                 333 
                 469 
               
               
                   
                 Average 
                 nd 
                 nd 
                 nd 
                 nd 
                 647 
                 452 
               
               
                   
                 Stdev 
                 nd 
                 nd 
                 nd 
                 nd 
                 751 
                 285 
               
               
                   
                 p (t-test) 
                 nd 
                 nd 
                 nd 
                 nd 
                   
                 0.53 
               
               
                   
                 Min 
                 nd 
                 nd 
                 nd 
                 nd 
                 48.0 
                 112 
               
               
                   
                 Max 
                 nd 
                 nd 
                 nd 
                 nd 
                 3370 
                 832 
               
               
                   
                 n (Samp) 
                 nd 
                 nd 
                 nd 
                 nd 
                 477 
                 6 
               
               
                   
                 n (Patient) 
                 nd 
                 nd 
                 nd 
                 nd 
                 216 
                 6 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 325 
                 303 
                 325 
                 314 
                 325 
                 524 
               
               
                   
                 Average 
                 586 
                 638 
                 586 
                 745 
                 586 
                 760 
               
               
                   
                 Stdev 
                 671 
                 810 
                 671 
                 893 
                 671 
                 827 
               
               
                   
                 p (t-test) 
                   
                 0.70 
                   
                 0.19 
                   
                 0.30 
               
               
                   
                 Min 
                 74.7 
                 113 
                 74.7 
                 48.0 
                 74.7 
                 119 
               
               
                   
                 Max 
                 3370 
                 2880 
                 3370 
                 3200 
                 3370 
                 2810 
               
               
                   
                 n (Samp) 
                 347 
                 28 
                 347 
                 36 
                 347 
                 17 
               
               
                   
                 n (Patient) 
                 167 
                 28 
                 167 
                 36 
                 167 
                 17 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.52 
                 nd 
                 0.49 
                 0.54 
                 nd 
                 0.52 
                 0.54 
                 0.50 
                 0.55 
               
               
                 SE 
                 0.057 
                 nd 
                 0.057 
                 0.051 
                 nd 
                 0.051 
                 0.069 
                 0.12 
                 0.073 
               
               
                 p 
                 0.76 
                 nd 
                 0.89 
                 0.48 
                 nd 
                 0.67 
                 0.54 
                 0.97 
                 0.53 
               
               
                 nCohort 1 
                 357 
                 nd 
                 347 
                 357 
                 nd 
                 347 
                 357 
                 477 
                 347 
               
               
                 nCohort 2 
                 28 
                 nd 
                 28 
                 37 
                 nd 
                 36 
                 19 
                 6 
                 17 
               
               
                 Cutoff 1 
                 246 
                 nd 
                 246 
                 228 
                 nd 
                 227 
                 184 
                 194 
                 194 
               
               
                 Sens 1 
                 71% 
                 nd 
                 71% 
                 70% 
                 nd 
                 72% 
                 74% 
                 83% 
                 71% 
               
               
                 Spec 1 
                 37% 
                 nd 
                 35% 
                 33% 
                 nd 
                 31% 
                 22% 
                 23% 
                 22% 
               
               
                 Cutoff 2 
                 168 
                 nd 
                 168 
                 191 
                 nd 
                 191 
                 141 
                 194 
                 183 
               
               
                 Sens 2 
                 82% 
                 nd 
                 82% 
                 81% 
                 nd 
                 81% 
                 84% 
                 83% 
                 82% 
               
               
                 Spec 2 
                 19% 
                 nd 
                 17% 
                 24% 
                 nd 
                 22% 
                 13% 
                 23% 
                 20% 
               
               
                 Cutoff 3 
                 141 
                 nd 
                 141 
                 112 
                 nd 
                 111 
                 118 
                 111 
                 128 
               
               
                 Sens 3 
                 93% 
                 nd 
                 93% 
                 92% 
                 nd 
                 92% 
                 95% 
                 100%  
                 94% 
               
               
                 Spec 3 
                 13% 
                 nd 
                 11% 
                  4% 
                 nd 
                  3% 
                  6% 
                  4% 
                  8% 
               
               
                 Cutoff 4 
                 502 
                 nd 
                 512 
                 502 
                 nd 
                 512 
                 502 
                 535 
                 512 
               
               
                 Sens 4 
                 29% 
                 nd 
                 25% 
                 41% 
                 nd 
                 42% 
                 53% 
                 50% 
                 53% 
               
               
                 Spec 4 
                 70% 
                 nd 
                 70% 
                 70% 
                 nd 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 833 
                 nd 
                 841 
                 833 
                 nd 
                 841 
                 833 
                 940 
                 841 
               
               
                 Sens 5 
                 18% 
                 nd 
                 18% 
                 24% 
                 nd 
                 25% 
                 21% 
                  0% 
                 24% 
               
               
                 Spec 5 
                 80% 
                 nd 
                 80% 
                 80% 
                 nd 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 1410 
                 nd 
                 1400 
                 1410 
                 nd 
                 1400 
                 1410 
                 1860 
                 1400 
               
               
                 Sens 6 
                 14% 
                 nd 
                 14% 
                 19% 
                 nd 
                 19% 
                 16% 
                  0% 
                 18% 
               
               
                 Spec 6 
                 90% 
                 nd 
                 90% 
                 90% 
                 nd 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 1.0 
                 nd 
                 1.2 
                 0.99 
                 nd 
                 1.2 
                 0.32 
                 2.0 
                 0.32 
               
               
                 p Value 
                 1.0 
                 nd 
                 0.77 
                 0.98 
                 nd 
                 0.65 
                 0.17 
                 0.57 
                 0.17 
               
               
                 95% CI of 
                 0.34 
                 nd 
                 0.38 
                 0.38 
                 nd 
                 0.49 
                 0.063 
                 0.18 
                 0.063 
               
               
                 OR Quart 2 
                 3.0 
                 nd 
                 3.7 
                 2.6 
                 nd 
                 3.1 
                 1.6 
                 23 
                 1.6 
               
               
                 OR Quart 3 
                 1.0 
                 nd 
                 1.4 
                 0.88 
                 nd 
                 0.64 
                 0.65 
                 1.0 
                 0.65 
               
               
                 p Value 
                 1.0 
                 nd 
                 0.58 
                 0.80 
                 nd 
                 0.41 
                 0.52 
                 1.0 
                 0.52 
               
               
                 95% CI of 
                 0.34 
                 nd 
                 0.45 
                 0.32 
                 nd 
                 0.22 
                 0.18 
                 0.062 
                 0.18 
               
               
                 OR Quart 3 
                 3.0 
                 nd 
                 4.1 
                 2.4 
                 nd 
                 1.9 
                 2.4 
                 16 
                 2.4 
               
               
                 OR Quart 4 
                 0.99 
                 nd 
                 1.2 
                 1.2 
                 nd 
                 1.1 
                 1.2 
                 2.0 
                 0.82 
               
               
                 p Value 
                 0.98 
                 nd 
                 0.76 
                 0.65 
                 nd 
                 0.83 
                 0.77 
                 0.56 
                 0.76 
               
               
                 95% CI of 
                 0.33 
                 nd 
                 0.39 
                 0.49 
                 nd 
                 0.43 
                 0.38 
                 0.18 
                 0.24 
               
               
                 OR Quart 4 
                 2.9 
                 nd 
                 3.7 
                 3.1 
                 nd 
                 2.9 
                 3.7 
                 23 
                 2.8 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 Comparison of marker levels in EDTA samples collected within 12 
               
               
                 hours of reaching stage R from Cohort 1 (patients that reached, but did 
               
               
                 not progress beyond, RIFLE stage R) and from Cohort 2 (patients that 
               
               
                 reached RIFLE stage I or F). 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
               
               
                   
                 1 
                 2 
                 1 
                 2 
                 1 
                 2 
               
               
                   
               
               
                 Median 
                 316 
                 336 
                 nd 
                 nd 
                 335 
                 348 
               
               
                 Average 
                 608 
                 776 
                 nd 
                 nd 
                 591 
                 728 
               
               
                 Stdev 
                 666 
                 936 
                 nd 
                 nd 
                 664 
                 883 
               
               
                 p (t-test) 
                   
                 0.32 
                 nd 
                 nd 
                   
                 0.45 
               
               
                 Min 
                 74.7 
                 110 
                 nd 
                 nd 
                 74.7 
                 110 
               
               
                 Max 
                 3200 
                 3170 
                 nd 
                 nd 
                 3200 
                 3170 
               
               
                 n (Samp) 
                 67 
                 30 
                 nd 
                 nd 
                 51 
                 26 
               
               
                 n (Patient) 
                 67 
                 30 
                 nd 
                 nd 
                 51 
                 26 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 At Enrollment 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
                   
               
               
                   
                 AUC 
                 0.53 
                 nd 
                 0.52 
               
               
                   
                 SE 
                 0.064 
                 nd 
                 0.070 
               
               
                   
                 p 
                 0.65 
                 nd 
                 0.75 
               
               
                   
                 nCohort 1 
                 67 
                 nd 
                 51 
               
               
                   
                 nCohort 2 
                 30 
                 nd 
                 26 
               
               
                   
                 Cutoff 1 
                 262 
                 nd 
                 219 
               
               
                   
                 Sens 1 
                 70% 
                 nd 
                 73% 
               
               
                   
                 Spec 1 
                 39% 
                 nd 
                 27% 
               
               
                   
                 Cutoff 2 
                 194 
                 nd 
                 186 
               
               
                   
                 Sens 2 
                 80% 
                 nd 
                 81% 
               
               
                   
                 Spec 2 
                 19% 
                 nd 
                 18% 
               
               
                   
                 Cutoff 3 
                 173 
                 nd 
                 159 
               
               
                   
                 Sens 3 
                 90% 
                 nd 
                 92% 
               
               
                   
                 Spec 3 
                 19% 
                 nd 
                 18% 
               
               
                   
                 Cutoff 4 
                 685 
                 nd 
                 538 
               
               
                   
                 Sens 4 
                 27% 
                 nd 
                 27% 
               
               
                   
                 Spec 4 
                 70% 
                 nd 
                 71% 
               
               
                   
                 Cutoff 5 
                 900 
                 nd 
                 849 
               
               
                   
                 Sens 5 
                 27% 
                 nd 
                 23% 
               
               
                   
                 Spec 5 
                 81% 
                 nd 
                 80% 
               
               
                   
                 Cutoff 6 
                 1410 
                 nd 
                 1200 
               
               
                   
                 Sens 6 
                 20% 
                 nd 
                 19% 
               
               
                   
                 Spec 6 
                 91% 
                 nd 
                 90% 
               
               
                   
                 OR Quart 2 
                 1.0 
                 nd 
                 1.3 
               
               
                   
                 p Value 
                 1.0 
                 nd 
                 0.73 
               
               
                   
                 95% CI of 
                 0.29 
                 nd 
                 0.33 
               
               
                   
                 OR Quart 2 
                 3.5 
                 nd 
                 4.8 
               
               
                   
                 OR Quart 3 
                 1.2 
                 nd 
                 1.3 
               
               
                   
                 p Value 
                 0.76 
                 nd 
                 0.73 
               
               
                   
                 95% CI of 
                 0.36 
                 nd 
                 0.33 
               
               
                   
                 OR Quart 3 
                 4.1 
                 nd 
                 4.8 
               
               
                   
                 OR Quart 4 
                 1.1 
                 nd 
                 0.93 
               
               
                   
                 p Value 
                 0.83 
                 nd 
                 0.91 
               
               
                   
                 95% CI of 
                 0.34 
                 nd 
                 0.24 
               
               
                   
                 OR Quart 4 
                 3.9 
                 nd 
                 3.6 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
               
                   
               
               
                 Comparison of the maximum marker levels in EDTA samples 
               
               
                 collected from Cohort 1 (patients that did not progress beyond RIFLE stage 0) and the 
               
               
                 maximum values in EDTA samples collected from subjects between enrollment and 0, 24 
               
               
                 hours, and 48 hours prior to reaching stage F in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 345 
                 698 
                 345 
                 698 
                 345 
                 663 
               
               
                   
                 Average 
                 612 
                 1270 
                 612 
                 1090 
                 612 
                 578 
               
               
                   
                 Stdev 
                 733 
                 1050 
                 733 
                 877 
                 733 
                 270 
               
               
                   
                 p (t-test) 
                   
                 0.0093 
                   
                 0.047 
                   
                 0.91 
               
               
                   
                 Min 
                 86.8 
                 231 
                 86.8 
                 231 
                 86.8 
                 231 
               
               
                   
                 Max 
                 3370 
                 3200 
                 3370 
                 3200 
                 3370 
                 932 
               
               
                   
                 n (Samp) 
                 90 
                 11 
                 90 
                 11 
                 90 
                 6 
               
               
                   
                 n (Patient) 
                 90 
                 11 
                 90 
                 11 
                 90 
                 6 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 338 
                 655 
                 338 
                 655 
                 338 
                 655 
               
               
                   
                 Average 
                 707 
                 576 
                 707 
                 576 
                 707 
                 576 
               
               
                   
                 Stdev 
                 844 
                 270 
                 844 
                 270 
                 844 
                 270 
               
               
                   
                 p (t-test) 
                   
                 0.70 
                   
                 0.70 
                   
                 0.70 
               
               
                   
                 Min 
                 86.8 
                 231 
                 86.8 
                 231 
                 86.8 
                 231 
               
               
                   
                 Max 
                 3370 
                 932 
                 3370 
                 932 
                 3370 
                 932 
               
               
                   
                 n (Samp) 
                 178 
                 6 
                 178 
                 6 
                 178 
                 6 
               
               
                   
                 n (Patient) 
                 178 
                 6 
                 178 
                 6 
                 178 
                 6 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 355 
                 1390 
                 355 
                 1280 
                 nd 
                 nd 
               
               
                   
                 Average 
                 632 
                 1680 
                 632 
                 1410 
                 nd 
                 nd 
               
               
                   
                 Stdev 
                 702 
                 1110 
                 702 
                 948 
                 nd 
                 nd 
               
               
                   
                 p (t-test) 
                   
                 4.0E−4 
                   
                 0.0068 
                 nd 
                 nd 
               
               
                   
                 Min 
                 86.8 
                 618 
                 86.8 
                 618 
                 nd 
                 nd 
               
               
                   
                 Max 
                 3370 
                 3200 
                 3370 
                 3200 
                 nd 
                 nd 
               
               
                   
                 n (Samp) 
                 94 
                 7 
                 94 
                 7 
                 nd 
                 nd 
               
               
                   
                 n (Patient) 
                 94 
                 7 
                 94 
                 7 
                 nd 
                 nd 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.76 
                 0.62 
                 0.85 
                 0.75 
                 0.62 
                 0.83 
                 0.64 
                 0.62 
                 nd 
               
               
                 SE 
                 0.087 
                 0.12 
                 0.093 
                 0.088 
                 0.12 
                 0.097 
                 0.13 
                 0.12 
                 nd 
               
               
                 p 
                 0.0029 
                 0.35 
                 1.8E−4 
                 0.0046 
                 0.35 
                 7.3E−4 
                 0.25 
                 0.35 
                 nd 
               
               
                 nCohort 1 
                 90 
                 178 
                 94 
                 90 
                 178 
                 94 
                 90 
                 178 
                 nd 
               
               
                 nCohort 2 
                 11 
                 6 
                 7 
                 11 
                 6 
                 7 
                 6 
                 6 
                 nd 
               
               
                 Cutoff 1 
                 626 
                 280 
                 689 
                 626 
                 280 
                 689 
                 278 
                 280 
                 nd 
               
               
                 Sens 1 
                 73% 
                 83% 
                 71% 
                 73% 
                 83% 
                 71% 
                 83% 
                 83% 
                 nd 
               
               
                 Spec 1 
                 74% 
                 43% 
                 74% 
                 74% 
                 43% 
                 74% 
                 42% 
                 43% 
                 nd 
               
               
                 Cutoff 2 
                 591 
                 280 
                 626 
                 591 
                 280 
                 626 
                 278 
                 280 
                 nd 
               
               
                 Sens 2 
                 82% 
                 83% 
                 86% 
                 82% 
                 83% 
                 86% 
                 83% 
                 83% 
                 nd 
               
               
                 Spec 2 
                 73% 
                 43% 
                 71% 
                 73% 
                 43% 
                 71% 
                 42% 
                 43% 
                 nd 
               
               
                 Cutoff 3 
                 278 
                 228 
                 591 
                 278 
                 228 
                 591 
                 228 
                 228 
                 nd 
               
               
                 Sens 3 
                 91% 
                 100%  
                 100%  
                 91% 
                 100%  
                 100%  
                 100%  
                 100%  
                 nd 
               
               
                 Spec 3 
                 42% 
                 30% 
                 70% 
                 42% 
                 30% 
                 70% 
                 34% 
                 30% 
                 nd 
               
               
                 Cutoff 4 
                 475 
                 578 
                 591 
                 475 
                 578 
                 591 
                 475 
                 578 
                 nd 
               
               
                 Sens 4 
                 82% 
                 67% 
                 100%  
                 82% 
                 67% 
                 100%  
                 67% 
                 67% 
                 nd 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 nd 
               
               
                 Cutoff 5 
                 754 
                 946 
                 933 
                 754 
                 946 
                 933 
                 754 
                 946 
                 nd 
               
               
                 Sens 5 
                 45% 
                  0% 
                 57% 
                 45% 
                  0% 
                 57% 
                 17% 
                  0% 
                 nd 
               
               
                 Spec 5 
                 80% 
                 80% 
                 81% 
                 80% 
                 80% 
                 81% 
                 80% 
                 80% 
                 nd 
               
               
                 Cutoff 6 
                 1660 
                 2040 
                 1810 
                 1660 
                 2040 
                 1810 
                 1660 
                 2040 
                 nd 
               
               
                 Sens 6 
                 27% 
                  0% 
                 43% 
                 18% 
                  0% 
                  29% 
                  0% 
                  0% 
                 nd 
               
               
                 Spec 6 
                 90% 
                 90% 
                 91% 
                 90% 
                 90% 
                 91% 
                 90% 
                 90% 
                 nd 
               
               
                 OR Quart 2 
                 &gt;2.2 
                 &gt;2.1 
                 &gt;0 
                 &gt;2.2 
                 &gt;2.1 
                 &gt;0 
                 &gt;2.2 
                 &gt;2.1 
                 nd 
               
               
                 p Value 
                 &lt;0.54 
                 &lt;0.55 
                 &lt;na 
                 &lt;0.54 
                 &lt;0.55 
                 &lt;na 
                 &lt;0.54 
                 &lt;0.55 
                 nd 
               
               
                 95% CI of 
                 &gt;0.18 
                 &gt;0.18 
                 &gt;na 
                 &gt;0.18 
                 &gt;0.18 
                 &gt;na 
                 &gt;0.18 
                 &gt;0.18 
                 nd 
               
               
                 OR Quart 2 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 nd 
               
               
                 OR Quart 3 
                 &gt;4.8 
                 &gt;3.2 
                 &gt;3.4 
                 &gt;4.8 
                 &gt;3.2 
                 &gt;3.4 
                 &gt;1.0 
                 &gt;3.2 
                 nd 
               
               
                 p Value 
                 &lt;0.18 
                 &lt;0.32 
                 &lt;0.30 
                 &lt;0.18 
                 &lt;0.32 
                 &lt;0.30 
                 &lt;0.98 
                 &lt;0.32 
                 nd 
               
               
                 95% CI of 
                 &gt;0.49 
                 &gt;0.32 
                 &gt;0.33 
                 &gt;0.49 
                 &gt;0.32 
                 &gt;0.33 
                 &gt;0.062 
                 &gt;0.32 
                 nd 
               
               
                 OR Quart 3 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 nd 
               
               
                 OR Quart 4 
                 &gt;6.0 
                 &gt;1.0 
                 &gt;4.5 
                 &gt;6.0 
                 &gt;1.0 
                 &gt;4.5 
                 &gt;3.4 
                 &gt;1.0 
                 nd 
               
               
                 p Value 
                 &lt;0.12 
                 &lt;0.99 
                 &lt;0.19 
                 &lt;0.12 
                 &lt;0.99 
                 &lt;0.19 
                 &lt;0.30 
                 &lt;0.99 
                 nd 
               
               
                 95% CI of 
                 &gt;0.64 
                 &gt;0.062 
                 &gt;0.47 
                 &gt;0.64 
                 &gt;0.062 
                 &gt;0.47 
                 &gt;0.33 
                 &gt;0.062 
                 nd 
               
               
                 OR Quart 4 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 na 
                 nd 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 9 
               
               
                   
               
               
                 Comparison of marker levels in urine samples collected from Cohort 
               
               
                 1 (patients that did not progress beyond RIFLE stage 0, R, or I) and in urine samples 
               
               
                 collected from Cohort 2 (subjects who progress to RIFLE stage F) at 0, 24 hours, and 48 
               
               
                 hours prior to the subject reaching RIFLE stage I. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 1300 
                 2590 
                 1300 
                 3200 
                 1300 
                 2010 
               
               
                   
                 Average 
                 1670 
                 2900 
                 1670 
                 3320 
                 1670 
                 2430 
               
               
                   
                 Stdev 
                 1300 
                 1820 
                 1300 
                 1750 
                 1300 
                 1860 
               
               
                   
                 p (t-test) 
                   
                 1.9E−7 
                   
                 4.1E−11 
                   
                 0.020 
               
               
                   
                 Min 
                 41.6 
                 390 
                 41.6 
                 687 
                 41.6 
                 81.2 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6190 
               
               
                   
                 n (Samp) 
                 1703 
                 31 
                 1703 
                 28 
                 1703 
                 16 
               
               
                   
                 n (Patient) 
                 580 
                 31 
                 580 
                 28 
                 580 
                 16 
               
               
                   
                 sCr only 
               
               
                   
                 Median 
                 1360 
                 2480 
                 1360 
                 2500 
                 1360 
                 1880 
               
               
                   
                 Average 
                 1750 
                 2480 
                 1750 
                 2860 
                 1750 
                 2240 
               
               
                   
                 Stdev 
                 1390 
                 1900 
                 1390 
                 1150 
                 1390 
                 1120 
               
               
                   
                 p (t-test) 
                   
                 0.083 
                   
                 0.012 
                   
                 0.30 
               
               
                   
                 Min 
                 41.6 
                 565 
                 41.6 
                 1430 
                 41.6 
                 1040 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 5000 
                 6400 
                 4360 
               
               
                   
                 n (Samp) 
                 1782 
                 11 
                 1782 
                 10 
                 1782 
                 9 
               
               
                   
                 n (Patient) 
                 600 
                 11 
                 600 
                 10 
                 600 
                 9 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 1380 
                 3210 
                 1380 
                 3220 
                 1380 
                 3480 
               
               
                   
                 Average 
                 1720 
                 3380 
                 1720 
                 3530 
                 1720 
                 3040 
               
               
                   
                 Stdev 
                 1300 
                 1950 
                 1300 
                 1930 
                 1300 
                 2330 
               
               
                   
                 p (t-test) 
                   
                 2.4E−8 
                   
                 1.1E−11 
                   
                 0.0045 
               
               
                   
                 Min 
                 41.6 
                 390 
                 41.6 
                 687 
                 41.6 
                 379 
               
               
                   
                 Max 
                 6400 
                 6400 
                 6400 
                 6400 
                 6400 
                 6190 
               
               
                   
                 n (Samp) 
                 1587 
                 20 
                 1587 
                 25 
                 1587 
                 8 
               
               
                   
                 n (Patient) 
                 499 
                 20 
                 499 
                 25 
                 499 
                 8 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 0.71 
                 0.62 
                 0.75 
                 0.78 
                 0.78 
                 0.78 
                 0.61 
                 0.67 
                 0.63 
               
               
                 SE 
                 0.053 
                 0.091 
                 0.063 
                 0.052 
                 0.087 
                 0.055 
                 0.075 
                 0.100 
                 0.11 
               
               
                 p 
                 7.5E−5 
                 0.20 
                 7.1E−5 
                 4.9E−8 
                 0.0015 
                 5.5E−7 
                 0.14 
                 0.097 
                 0.22 
               
               
                 nCohort 1 
                 1703 
                 1782 
                 1587 
                 1703 
                 1782 
                 1587 
                 1703 
                 1782 
                 1587 
               
               
                 nCohort 2 
                 31 
                 11 
                 20 
                 28 
                 10 
                 25 
                 16 
                 9 
                 8 
               
               
                 Cutoff 1 
                 1660 
                 1070 
                 2470 
                 2450 
                 2270 
                 2450 
                 1040 
                 1420 
                 480 
               
               
                 Sens 1 
                 71% 
                 73% 
                 70% 
                 71% 
                 70% 
                 72% 
                 75% 
                 78% 
                 75% 
               
               
                 Spec 1 
                 62% 
                 40% 
                 78% 
                 79% 
                 74% 
                 78% 
                 39% 
                 52% 
                 14% 
               
               
                 Cutoff 2 
                 1030 
                 934 
                 1660 
                 1440 
                 2010 
                 1540 
                 480 
                 1310 
                 471 
               
               
                 Sens 2 
                 81% 
                 82% 
                 80% 
                 82% 
                 80% 
                 80% 
                 81% 
                 89% 
                 88% 
               
               
                 Spec 2 
                 39% 
                 34% 
                 60% 
                 55% 
                 68% 
                 56% 
                 15% 
                 49% 
                 13% 
               
               
                 Cutoff 3 
                 874 
                 577 
                 874 
                 819 
                 1960 
                 808 
                 378 
                 1040 
                 378 
               
               
                 Sens 3 
                 90% 
                 91% 
                 90% 
                 93% 
                 90% 
                 92% 
                 94% 
                 100%  
                 100%  
               
               
                 Spec 3 
                 32% 
                 19% 
                 30% 
                 30% 
                 67% 
                 28% 
                 10% 
                 38% 
                  9% 
               
               
                 Cutoff 4 
                 1990 
                 2070 
                 2050 
                 1990 
                 2070 
                 2050 
                 1990 
                 2070 
                 2050 
               
               
                 Sens 4 
                 65% 
                 55% 
                 70% 
                 75% 
                 70% 
                 76% 
                 50% 
                 44% 
                 62% 
               
               
                 Spec 4 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
                 70% 
               
               
                 Cutoff 5 
                 2560 
                 2710 
                 2650 
                 2560 
                 2710 
                 2650 
                 2560 
                 2710 
                 2650 
               
               
                 Sens 5 
                 52% 
                 36% 
                 55% 
                 61% 
                 40% 
                 64% 
                 38% 
                 22% 
                 62% 
               
               
                 Spec 5 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
                 80% 
               
               
                 Cutoff 6 
                 3620 
                 3850 
                 3690 
                 3620 
                 3850 
                 3690 
                 3620 
                 3850 
                 3690 
               
               
                 Sens 6 
                 29% 
                 18% 
                 45% 
                 39% 
                 20% 
                 48% 
                 25% 
                 11% 
                 38% 
               
               
                 Spec 6 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
                 90% 
               
               
                 OR Quart 2 
                 1.7 
                 1.0 
                 3.0 
                 2.0 
                 &gt;0 
                 4.0 
                 0.25 
                 &gt;2.0 
                 0 
               
               
                 p Value 
                 0.48 
                 1.0 
                 0.34 
                 0.57 
                 &lt;na 
                 0.21 
                 0.21 
                 &lt;0.57 
                 na 
               
               
                 95% CI of 
                 0.40 
                 0.14 
                 0.31 
                 0.18 
                 &gt;na 
                 0.45 
                 0.028 
                 &gt;0.18 
                 na 
               
               
                 OR Quart 2 
                 7.0 
                 7.1 
                 29 
                 22 
                 na 
                 36 
                 2.2 
                 na 
                 na 
               
               
                 OR Quart 3 
                 1.3 
                 0.50 
                 2.0 
                 5.0 
                 &gt;4.0 
                 2.0 
                 1.00 
                 &gt;4.0 
                 0 
               
               
                 p Value 
                 0.71 
                 0.57 
                 0.57 
                 0.14 
                 &lt;0.21 
                 0.57 
                 1.00 
                 &lt;0.21 
                 na 
               
               
                 95% CI of 
                 0.30 
                 0.045 
                 0.18 
                 0.59 
                 &gt;0.45 
                 0.18 
                 0.25 
                 &gt;0.45 
                 na 
               
               
                 OR Quart 3 
                 6.0 
                 5.5 
                 22 
                 43 
                 na 
                 22 
                 4.0 
                 na 
                 na 
               
               
                 OR Quart 4 
                 6.6 
                 3.0 
                 14 
                 21 
                 &gt;6.1 
                 19 
                 1.8 
                 &gt;3.0 
                 1.7 
               
               
                 p Value 
                 0.0026 
                 0.18 
                 0.010 
                 0.0031 
                 &lt;0.095 
                 0.0044 
                 0.37 
                 &lt;0.34 
                 0.48 
               
               
                 95% CI of 
                 1.9 
                 0.61 
                 1.9 
                 2.8 
                 &gt;0.73 
                 2.5 
                 0.51 
                 &gt;0.31 
                 0.40 
               
               
                 OR Quart 4 
                 22 
                 15 
                 110 
                 160 
                 na 
                 140 
                 6.1 
                 na 
                 7.0 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Comparison of marker levels in EDTA samples collected from 
               
               
                 Cohort 1 (patients that did not progress beyond RIFLE stage 0, R, or I) and in EDTA 
               
               
                 samples collected from Cohort 2 (subjects who progress to RIFLE stage F) at 0, 24 hours, 
               
               
                 and 48 hours prior to the subject reaching RIFLE stage I. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                   
                 24 hr prior to AKI stage 
                   
                 48 hr prior to AKI stage 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
                 Cohort 1 
                 Cohort 2 
               
               
                   
                   
               
               
                   
                 sCr or UO 
               
               
                   
                 Median 
                 nd 
                 nd 
                 326 
                 618 
                 nd 
                 nd 
               
               
                   
                 Average 
                 nd 
                 nd 
                 606 
                 1130 
                 nd 
                 nd 
               
               
                   
                 Stdev 
                 nd 
                 nd 
                 706 
                 1140 
                 nd 
                 nd 
               
               
                   
                 p (t-test) 
                 nd 
                 nd 
                   
                 0.054 
                 nd 
                 nd 
               
               
                   
                 Min 
                 nd 
                 nd 
                 48.0 
                 190 
                 nd 
                 nd 
               
               
                   
                 Max 
                 nd 
                 nd 
                 3370 
                 3200 
                 nd 
                 nd 
               
               
                   
                 n (Samp) 
                 nd 
                 nd 
                 489 
                 7 
                 nd 
                 nd 
               
               
                   
                 n (Patient) 
                 nd 
                 nd 
                 222 
                 7 
                 nd 
                 nd 
               
               
                   
                 UO only 
               
               
                   
                 Median 
                 nd 
                 nd 
                 326 
                 1000 
                 nd 
                 nd 
               
               
                   
                 Average 
                 nd 
                 nd 
                 604 
                 1340 
                 nd 
                 nd 
               
               
                   
                 Stdev 
                 nd 
                 nd 
                 698 
                 1110 
                 nd 
                 nd 
               
               
                   
                 p (t-test) 
                 nd 
                 nd 
                   
                 0.011 
                 nd 
                 nd 
               
               
                   
                 Min 
                 nd 
                 nd 
                 48.0 
                 279 
                 nd 
                 nd 
               
               
                   
                 Max 
                 nd 
                 nd 
                 3370 
                 3200 
                 nd 
                 nd 
               
               
                   
                 n (Samp) 
                 nd 
                 nd 
                 485 
                 6 
                 nd 
                 nd 
               
               
                   
                 n (Patient) 
                 nd 
                 nd 
                 208 
                 6 
                 nd 
                 nd 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 hr prior to AKI stage 
                 24 hr prior to AKI stage 
                 48 hr prior to AKI stage 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
               
               
                 AUC 
                 nd 
                 nd 
                 nd 
                 0.64 
                 nd 
                 0.78 
                 nd 
                 nd 
                 nd 
               
               
                 SE 
                 nd 
                 nd 
                 nd 
                 0.11 
                 nd 
                 0.11 
                 nd 
                 nd 
                 nd 
               
               
                 p 
                 nd 
                 nd 
                 nd 
                 0.21 
                 nd 
                 0.012 
                 nd 
                 nd 
                 nd 
               
               
                 nCohort 1 
                 nd 
                 nd 
                 nd 
                 489 
                 nd 
                 485 
                 nd 
                 nd 
                 nd 
               
               
                 nCohort 2 
                 nd 
                 nd 
                 nd 
                 7 
                 nd 
                 6 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 1 
                 nd 
                 nd 
                 nd 
                 278 
                 nd 
                 560 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 1 
                 nd 
                 nd 
                 nd 
                 71% 
                 nd 
                 83% 
                 nd 
                 nd 
                 nd 
               
               
                 Spec 1 
                 nd 
                 nd 
                 nd 
                 42% 
                 nd 
                 73% 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 2 
                 nd 
                 nd 
                 nd 
                 228 
                 nd 
                 560 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 2 
                 nd 
                 nd 
                 nd 
                 86% 
                 nd 
                 83% 
                 nd 
                 nd 
                 nd 
               
               
                 Spec 2 
                 nd 
                 nd 
                 nd 
                 31% 
                 nd 
                 73% 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 3 
                 nd 
                 nd 
                 nd 
                 190 
                 nd 
                 278 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 3 
                 nd 
                 nd 
                 nd 
                 100%  
                 nd 
                 100%  
                 nd 
                 nd 
                 nd 
               
               
                 Spec 3 
                 nd 
                 nd 
                 nd 
                 22% 
                 nd 
                 42% 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 4 
                 nd 
                 nd 
                 nd 
                 515 
                 nd 
                 518 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 4 
                 nd 
                 nd 
                 nd 
                 57% 
                 nd 
                 83% 
                 nd 
                 nd 
                 nd 
               
               
                 Spec 4 
                 nd 
                 nd 
                 nd 
                 70% 
                 nd 
                 70% 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 5 
                 nd 
                 nd 
                 nd 
                 845 
                 nd 
                 833 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 5 
                 nd 
                 nd 
                 nd 
                 43% 
                 nd 
                 50% 
                 nd 
                 nd 
                 nd 
               
               
                 Spec 5 
                 nd 
                 nd 
                 nd 
                 80% 
                 nd 
                 80% 
                 nd 
                 nd 
                 nd 
               
               
                 Cutoff 6 
                 nd 
                 nd 
                 nd 
                 1670 
                 nd 
                 1660 
                 nd 
                 nd 
                 nd 
               
               
                 Sens 6 
                 nd 
                 nd 
                 nd 
                 29% 
                 nd 
                 33% 
                 nd 
                 nd 
                 nd 
               
               
                 Spec 6 
                 nd 
                 nd 
                 nd 
                 90% 
                 nd 
                 90% 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 2 
                 nd 
                 nd 
                 nd 
                 2.0 
                 nd 
                 &gt;1.0 
                 nd 
                 nd 
                 nd 
               
               
                 p Value 
                 nd 
                 nd 
                 nd 
                 0.57 
                 nd 
                 &lt;1.0 
                 nd 
                 nd 
                 nd 
               
               
                 95% CI of 
                 nd 
                 nd 
                 nd 
                 0.18 
                 nd 
                 &gt;0.062 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 2 
                 nd 
                 nd 
                 nd 
                 23 
                 nd 
                 na 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 3 
                 nd 
                 nd 
                 nd 
                 1.0 
                 nd 
                 &gt;2.0 
                 nd 
                 nd 
                 nd 
               
               
                 p Value 
                 nd 
                 nd 
                 nd 
                 1.0 
                 nd 
                 &lt;0.57 
                 nd 
                 nd 
                 nd 
               
               
                 95% CI of 
                 nd 
                 nd 
                 nd 
                 0.062 
                 nd 
                 &gt;0.18 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 3 
                 nd 
                 nd 
                 nd 
                 16 
                 nd 
                 na 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 4 
                 nd 
                 nd 
                 nd 
                 3.0 
                 nd 
                 &gt;3.0 
                 nd 
                 nd 
                 nd 
               
               
                 p Value 
                 nd 
                 nd 
                 nd 
                 0.34 
                 nd 
                 &lt;0.34 
                 nd 
                 nd 
                 nd 
               
               
                 95% CI of 
                 nd 
                 nd 
                 nd 
                 0.31 
                 nd 
                 &gt;0.31 
                 nd 
                 nd 
                 nd 
               
               
                 OR Quart 4 
                 nd 
                 nd 
                 nd 
                 30 
                 nd 
                 na 
                 nd 
                 nd 
                 nd 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 11 
               
               
                   
               
               
                 Comparison of marker levels in enroll urine samples collected from 
               
               
                 Cohort 1 (patients that did not progress beyond RIFLE stage 0 or R 
               
               
                 within 48 hrs) and in enroll urine samples collected from Cohort 2 
               
               
                 (subjects reaching RIFLE stage I or F within 48 hrs). Enroll samples 
               
               
                 from patients already at RIFLE stage I or F were included in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
               
               
                   
                 1 
                 2 
                 1 
                 2 
                 1 
                 2 
               
               
                   
               
               
                 Median 
                 1170 
                 2300 
                 1260 
                 2800 
                 1220 
                 2220 
               
               
                 Average 
                 1480 
                 2660 
                 1680 
                 2830 
                 1560 
                 2680 
               
               
                 Stdev 
                 1160 
                 1770 
                 1360 
                 1780 
                 1180 
                 1810 
               
               
                 p (t-test) 
                   
                 2.1E−18 
                   
                 2.0E−5 
                   
                 3.6E−14 
               
               
                 Min 
                 41.6 
                 81.2 
                 41.6 
                 197 
                 41.6 
                 81.2 
               
               
                 Max 
                 6300 
                 6400 
                 6400 
                 6390 
                 5430 
                 6400 
               
               
                 n (Samp) 
                 484 
                 129 
                 576 
                 28 
                 406 
                 110 
               
               
                 n (Patient) 
                 484 
                 129 
                 576 
                 28 
                 406 
                 110 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 At Enrollment 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
                   
               
               
                   
                 AUC 
                 0.70 
                 0.69 
                 0.69 
               
               
                   
                 SE 
                 0.028 
                 0.057 
                 0.030 
               
               
                   
                 p 
                 3.5E−13 
                 7.6E−4 
                 6.8E−10 
               
               
                   
                 nCohort 1 
                 484 
                 576 
                 406 
               
               
                   
                 nCohort 2 
                 129 
                 28 
                 110 
               
               
                   
                 Cutoff 1 
                 1380 
                 1450 
                 1380 
               
               
                   
                 Sens 1 
                 71% 
                 71% 
                 70% 
               
               
                   
                 Spec 1 
                 58% 
                 57% 
                 56% 
               
               
                   
                 Cutoff 2 
                 886 
                 808 
                 949 
               
               
                   
                 Sens 2 
                 81% 
                 82% 
                 80% 
               
               
                   
                 Spec 2 
                 38% 
                 32% 
                 38% 
               
               
                   
                 Cutoff 3 
                 616 
                 551 
                 674 
               
               
                   
                 Sens 3 
                 91% 
                 93% 
                 90% 
               
               
                   
                 Spec 3 
                 24% 
                 19% 
                 25% 
               
               
                   
                 Cutoff 4 
                 1760 
                 1990 
                 1880 
               
               
                   
                 Sens 4 
                 59% 
                 68% 
                 57% 
               
               
                   
                 Spec 4 
                 70% 
                 70% 
                 70% 
               
               
                   
                 Cutoff 5 
                 2280 
                 2660 
                 2440 
               
               
                   
                 Sens 5 
                 50% 
                 61% 
                 46% 
               
               
                   
                 Spec 5 
                 80% 
                 80% 
                 80% 
               
               
                   
                 Cutoff 6 
                 3190 
                 3790 
                 3310 
               
               
                   
                 Sens 6 
                 36% 
                 29% 
                 34% 
               
               
                   
                 Spec 6 
                 90% 
                 90% 
                 90% 
               
               
                   
                 OR Quart 2 
                 1.1 
                 0.39 
                 1.1 
               
               
                   
                 p Value 
                 0.86 
                 0.27 
                 0.85 
               
               
                   
                 95% CI of 
                 0.53 
                 0.075 
                 0.52 
               
               
                   
                 OR Quart 2 
                 2.2 
                 2.1 
                 2.2 
               
               
                   
                 OR Quart 3 
                 2.0 
                 0.79 
                 1.9 
               
               
                   
                 p Value 
                 0.030 
                 0.74 
                 0.069 
               
               
                   
                 95% CI of 
                 1.1 
                 0.21 
                 0.95 
               
               
                   
                 OR Quart 3 
                 3.9 
                 3.0 
                 3.7 
               
               
                   
                 OR Quart 4 
                 5.5 
                 3.7 
                 4.5 
               
               
                   
                 p Value 
                 2.0E−8 
                 0.012 
                 3.4E−6 
               
               
                   
                 95% CI of 
                 3.0 
                 1.3 
                 2.4 
               
               
                   
                 OR Quart 4 
                 10 
                 10 
                 8.4 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
               
                   
               
               
                 Comparison of marker levels in enroll EDTA samples collected 
               
               
                 from Cohort 1 (patients that did not progress beyond RIFLE stage 0 or 
               
               
                 R within 48 hrs) and in enroll EDTA samples collected from 
               
               
                 Cohort 2 (subjects reaching RIFLE stage I or F within 48 hrs). Enroll 
               
               
                 samples from patients already at stage I or F were included in Cohort 2. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
                 Cohort 
               
               
                   
                 1 
                 2 
                 1 
                 2 
                 1 
                 2 
               
               
                   
               
               
                 Median 
                 309 
                 266 
                 nd 
                 nd 
                 354 
                 247 
               
               
                 Average 
                 651 
                 674 
                 nd 
                 nd 
                 647 
                 679 
               
               
                 Stdev 
                 791 
                 841 
                 nd 
                 nd 
                 774 
                 856 
               
               
                 p (t-test) 
                   
                 0.89 
                 nd 
                 nd 
                   
                 0.85 
               
               
                 Min 
                 76.0 
                 48.0 
                 nd 
                 nd 
                 76.0 
                 48.0 
               
               
                 Max 
                 3350 
                 3200 
                 nd 
                 nd 
                 3350 
                 3200 
               
               
                 n (Samp) 
                 140 
                 29 
                 nd 
                 nd 
                 133 
                 28 
               
               
                 n (Patient) 
                 140 
                 29 
                 nd 
                 nd 
                 133 
                 28 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 At Enrollment 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 sCr or UO 
                 sCr only 
                 UO only 
               
               
                   
                   
               
               
                   
                 AUC 
                 0.48 
                 nd 
                 0.47 
               
               
                   
                 SE 
                 0.059 
                 nd 
                 0.061 
               
               
                   
                 p 
                 0.79 
                 nd 
                 0.61 
               
               
                   
                 nCohort 1 
                 140 
                 nd 
                 133 
               
               
                   
                 nCohort 2 
                 29 
                 nd 
                 28 
               
               
                   
                 Cutoff 1 
                 184 
                 nd 
                 184 
               
               
                   
                 Sens 1 
                 72% 
                 nd 
                 71% 
               
               
                   
                 Spec 1 
                 23% 
                 nd 
                 21% 
               
               
                   
                 Cutoff 2 
                 140 
                 nd 
                 140 
               
               
                   
                 Sens 2 
                 83% 
                 nd 
                 82% 
               
               
                   
                 Spec 2 
                 14% 
                 nd 
                 11% 
               
               
                   
                 Cutoff 3 
                 93.7 
                 nd 
                 93.7 
               
               
                   
                 Sens 3 
                 93% 
                 nd 
                 93% 
               
               
                   
                 Spec 3 
                  3% 
                 nd 
                  3% 
               
               
                   
                 Cutoff 4 
                 517 
                 nd 
                 538 
               
               
                   
                 Sens 4 
                 41% 
                 nd 
                 36% 
               
               
                   
                 Spec 4 
                 70% 
                 nd 
                 71% 
               
               
                   
                 Cutoff 5 
                 882 
                 nd 
                 882 
               
               
                   
                 Sens 5 
                 21% 
                 nd 
                 21% 
               
               
                   
                 Spec 5 
                 80% 
                 nd 
                 80% 
               
               
                   
                 Cutoff 6 
                 1860 
                 nd 
                 1860 
               
               
                   
                 Sens 6 
                 10% 
                 nd 
                 11% 
               
               
                   
                 Spec 6 
                 90% 
                 nd 
                 90% 
               
               
                   
                 OR Quart 2 
                 1.5 
                 nd 
                 1.2 
               
               
                   
                 p Value 
                 0.53 
                 nd 
                 0.73 
               
               
                   
                 95% CI of 
                 0.46 
                 nd 
                 0.38 
               
               
                   
                 OR Quart 2 
                 4.6 
                 nd 
                 4.1 
               
               
                   
                 OR Quart 3 
                 1.0 
                 nd 
                 1.0 
               
               
                   
                 p Value 
                 0.96 
                 nd 
                 0.96 
               
               
                   
                 95% CI of 
                 0.30 
                 nd 
                 0.30 
               
               
                   
                 OR Quart 3 
                 3.5 
                 nd 
                 3.5 
               
               
                   
                 OR Quart 4 
                 1.7 
                 nd 
                 1.7 
               
               
                   
                 p Value 
                 0.37 
                 nd 
                 0.37 
               
               
                   
                 95% CI of 
                 0.54 
                 nd 
                 0.54 
               
               
                   
                 OR Quart 4 
                 5.2 
                 nd 
                 5.3 
               
               
                   
                   
               
            
           
         
       
     
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     While the invention has been described and exemplified in sufficient detail for those skilled in this art to make and use it, various alternatives, modifications, and improvements should be apparent without departing from the spirit and scope of the invention. The examples provided herein are representative of preferred embodiments, are exemplary, and are not intended as limitations on the scope of the invention. Modifications therein and other uses will occur to those skilled in the art. These modifications are encompassed within the spirit of the invention and are defined by the scope of the claims. 
     It will be readily apparent to a person skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. 
     All patents and publications mentioned in the specification are indicative of the levels of those of ordinary skill in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. 
     The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. Thus, for example, in each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. 
     Other embodiments are set forth within the following claims.