Development of the Acute Decompensated Heart Failure Risk Model for emergency room resident training

ion study. Examples are quality of life questionnaires or certain serum laboratory results that were either not ordered or are not available. American College of Cardiology (ACC) and American Heart Association (AHA) guidelines, hospital specific practices and the clinical judgment of the physician are used to treat patients with acute decompensated heart who present in the emergency room. Many decisions based on commonly collected assessments in the emergency room must be made quickly and treatment initiated early. However, many of these therapeutic measures are contraindicated in patients whose blood pressure is low at presentation or chronically low (Abraham et al., 2008; Buiciuc et al., 2011; Gheorghiade et al., 2006; Miller & Skouri, 2009). These patients are considered sicker and are treated with drugs such as intravenously administered inotropes to improve cardiac output. Yet these same drugs are associated with increased morbidity and mortality. In addition, invasive monitoring is more common in these patients. Database analysis of several heart failure registries support improved outcomes when treatment is initiated early upon presentation in the emergency room (Abraham et al., 2008; Mebazaa et al., 2008; Subbe, Kruger, Rutherford, & Gemmel, 2001). Thus a quick risk stratification system to score patients presenting with acute decompensated heart failure has the potential to lead to effective individualized treatment modalities. Purpose of the Study The purpose of this study was to characterize patients hospitalized with acute decompensated heart failure with and without low systolic blood pressure using EFA. Patients requiring hospitalization due to acute decompensated heart failure present with distinct clinical characteristics including severe symptoms that necessitate rapid DEVELOPMENT OF THE RISK MODEL FOR RESIDENT TRAINING 7 treatment that cannot be delivered in an outpatient setting. Response to treatments varies, and those requiring invasive diagnostic procedures, coronary interventions or surgical treatments meet the guidelines for admission. Each patient presents with clinical signs and symptoms, a heart failure history, and comorbidities. Direct and surrogate measurements are then measured. Safety and cost-effective management is paramount, but there is a deluge of clinical data. The question investigated was could the method of data reduction using EFA elicit a parsimonious group of factors to summarize the relationship between these variables? A better understanding of the characteristics and outcomes of patients presented with acute decompensated heart failure with and without low systolic blood pressure could potentially lead to individualized treatment modalities tailored to effectively and economically improve care. Research Questions 1. What were the common factors in patients with acute decompensated heart failure? 2. What were the common factors in patients with acute decompensated heart failure and normal or high systolic blood pressure? 3. What were the common factors in patients with acute decompensated heart failure and low systolic blood pressure? 4. Was there a difference in the common factors in patients with and without low systolic blood pressure and acute decompensate heart failure? Operational Definitions (add as needed, definitions of signs and symptoms or other technical terms will be summarized in the appendices) DEVELOPMENT OF THE RISK MODEL FOR RESIDENT TRAINING 8 Acute decompensated heart failure: Acute heart failure syndrome is defined as gradual or rapid change in heart failure (HF) signs and symptoms resulting in a need for urgent therapy. Acute heart failure syndromes encompasses at least 3 clinical distinct entities: (1) Worsening chronic HF associated with reduced or preserved LVEF (70% of all admissions); (2) de novo HF (e.g., after a large MI; sudden increase in blood pressure superimposed on a noncompliant LV) (25% of all admissions); and (3) advanced HF (i.e., refractory to therapy) with severe LV systolic dysfunction, associated with a continually worsening low-output state (5% of all admissions) (Gheorghiade et al., 2005, pp. 35943959). Blood pressure: pressure exerted by the blood upon the walls of the blood vessels and especially arteries, usually measured on the radial artery by means of a sphygmomanometer, and expressed in millimeters of mercury either as a fraction having as numerator the maximum pressure that follows systole of the left ventricle of the heart and as denominator the minimum pressure that accompanies cardiac diastole or as a whole number representing the first value only a blood pressure of 120/80—abbreviation BP. Diastolic blood pressure is the lowest arterial blood pressure of a cardiac cycle occurring during diastole of the heart and systolic blood pressure is the highest arterial blood pressure of a cardiac cycle occurring immediately after systole of the left ventricle of the heart (Merriam-Webster, n.d.). Heart failure: Heart failure is a syndrome caused by cardiac dysfunction, generally resulting from myocardial muscle dysfunction or loss and characterized by left ventricular dilation or hypertrophy [or both]. Whether the dysfunction is primarily systolic or diastolic or mixed, it leads to neurohormonal and circulatory abnormalities, usually resulting in DEVELOPMENT OF THE RISK MODEL FOR RESIDENT TRAINING 9 characteristic symptoms such as fluid retention, shortness of breath, and fatigue, especially on exertion. In the absence of appropriate therapeutic intervention, heart failure is usually progressive at the level of both cardiac function and clinical symptoms. The severity of clinical symptoms may vary substantially during the course of the disease process and may not correlate with changes in underlying cardiac function. Although heart failure is progressive and often fatal, patients can be stabilized and myocardial dysfunction and remodeling may improve, either spontaneously or as a consequence of therapy. In physiologic terms, heart failure is a syndrome characterized by elevated cardiac filling pressure or inadequate peripheral oxygen delivery, at rest or during stress, caused by cardiac dysfunction (Lindenfeld & Arnold, 2006, p. e10). Heart failure with preserved ejection fraction: Also referred to as heart failure with a nondilated left ventricle. A clinical syndrome characterized by signs and symptoms of heart failure with preserved left ventricular ejection fraction. Most commonly associated with a nondilated left ventricular chamber. May be the results of valvular disease or other causes (Lindenfeld & Arnold, 2006, p. e10). Heart failure with reduced ejection fraction: Also referred to as heart failure with a dilated left ventricle. A clinical syndrome characterized by signs and symptoms of heart failure and reduced left ventricular ejection fraction. Most commonly associated with left ventricular chamber dilation (Lindenfeld & Arnold, 2006, p. e10). International Classification of Diseases, Ninth Revision, Clinical Modification code (ICD-9) code and classify morbidity data from the inpatient and outpatient records, physician offices, and most National Center for Health Statistics (NCHS) surveys (n.d., para 3). DEVELOPMENT OF THE RISK MODEL FOR RESIDENT TRAINING 10 Statistical Definitions The following statistical definitions were taken from Hair et al. (1992, p. 224). Common factor analysis: A factor model in which the factors are based upon a reduced correlation matrix. That is, communalities.are inserted in the diagonal of the correlation matrix, and the extracted factors are based only on the common variance, with specific and error variance excluded. Correlation matrix: A table showing the intercorrelations among all variables. Eigenvalue: The column sum of squares for a factor; also referred to as the latent root. It represents the amount of variance accounted for by a factor Factor: A linear combination of the original variables. Factors also represent the underlying dimensions (constructs) that summarize or account of the original set of observed variables Factor loadings: The correlation between the original variables and the factors, and the key to understanding the nature of a particular factor. Squared factor loadings indicate what percentage of the variance in an original variable is explained by a factor. Factor matrix: A table displacing the factor loadings of all variables on each factor. Factor score: Factor analysis reduces the original set of variables to a new smaller set of variables, or factors. When this new smaller set of variables (factors) is used in subsequent analysis (e.g., discriminant analysis), some measure or score must be included to represent the newly derived variables. This measure (score) is a composite of all of the original variables that were important in making the new factor. The composite measure is referred to as a factor score. DEVELOPMENT OF THE RISK MODEL FOR RESIDENT TRAINING 11 Orthogonal: Refers to the mathematical independent of factor axes to each other (i.e., at right angles, or 90 degrees). Orthogonal factor solutions: A factor solution in which the factors are extracted so that the factor axes are maintained at 90 degrees. Thus each factor is independent of, or orthogonal from, all other factors. The correlation between factors is arbitrarily determined to be zero. Trace: The sum of the squares of the numbers on the diagonal of the correlation matrix used in the factor analysis. It represents the total amount of variance on which the factor solution is based.With common factor analysis, the trace is equal to the sum of the communalities on the diagonal of he reduced correlation matrix (also equal to the amount of common variance of the variables being analyzed). Limitations The nature of limitations in this study included data selection and collection, the timing of the study and the statistical approach chosen. The data for this retrospective chart revie