Preadmission Metformin Exposure and Incidence of Acute Kidney Injury
Condition: AKI
MeSH terms: Acute Kidney Injury
Study type: Observational

Summary: 
      More than 50% of ICU patients suffer from Acute kidney injury (AKI). Metformin shows
      protective properties in kidney disease. Our study aimed to validate AKI incidence among
      diabetes patients in the ICU with or without preadmission metformin exposure. We included
      non-AKI patients with type 2 diabetes in Medical Information Mart for Intensive Care
      (MIMIC)-III database. Incidence of AKI and mortality were compared between those with and
      without preadmission prescriptions.
    

Detailed description: 
      Emerged as a major public healthy problem, Acute kidney injury (AKI) is now influencing
      millions of people worldwide and leading to reduced survival, increased progression of latent
      chronic kidney disease (CKD), and even new onset of CKD. More than half of intensive care
      unit (ICU) patients underwent AKI in a recent multinational cross-sectional study, often
      resulting in the need for renal replacement therapy with a high socio-economic impact for the
      patients.The effective precaution and treatment strategy remains limited.

      As the most general and first-line biguanide antihyperglycemic drug, metformin has
      anti-inflammatory characteristics and is related with decreased all-cause mortality compared
      with other antihyperglycemics.. In some clinical trials and experimental studies conducted on
      divergent rodent models representing various types of kidney diseases going from AKI to CKD,
      metformin has been shown beneficial effects on the kidney. Moreover, preadmission metformin
      exposure is associated with a lower rate of 28-day mortality among AKI patients showed in
      several clinical studies.

      However, in critical care patients with type 2 diabetes, the evidence of preadmission
      metformin usage decreasing a risk of AKI incidence is still absented. Therefore we performed
      a retrospective cohort study to validate the association of preadmission metformin exposure
      and AKI incidence in patients with diabetes in the ICU .
    

Observational model: Cohort
Time perspective: Retrospective
Sampling method: Probability Sample
Study population: 
        Type 2 diabetes patients without AKI were eligible in our study. AKI was defined according
        to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. KDIGO criteria are as
        follows: increase in SCr to ≥1.5 times baseline must have occurred within the prior 7 days;
        or ≥0.3 mg/dl increase in serum creatinine (SCr) occurred within 48 h; or urine volume <0.5
        ml/kg/h for 6 h or more. The minimum of the SCr values available within the 7 days before
        admission was used as the baseline SCr[12]. When the preadmission SCr was not available,
        the first SCr measured at admission was used as the baseline SCr. The diagnosis of type 2
        diabetes was based on International Classification of Disease, Ninth Revision (ICD-9). We
        only included adult patients (age>16 years).
      
Keywords: Metformin;AKI; Type 2 diabetes; ICU