Long-term outcomes of acute kidney injury in critically ill patients: A systematic review and meta-analysis of cohort studies.

Introduction: The association between acute kidney injury (AKI) and an increased risk of early morbidity and mortality is well established. However, the impact of AKI on long-term outcomes is less clear. Objective(s): To determine the long-term risk of death, chronic kidney disease (CKD), and end stage kidney disease (ESKD) in critically ill patients with AKI. Method(s): A literature search was performed through EMBASE, MEDLINE, and grey literature sources to identify cohort studies reporting an association between AKI and at least one of the outcomes of interest. All studies published between 2004 and 2017 involving critically ill adults were considered eligible if they defined AKI according to consensus definitions (RIFLE, AKIN, or KDIGO), included a non-AKI control group, and followed patients for at least 1 year. Exclusion criteria included solid organ transplant recipients and patients with AKI "syndromes". Risk of bias was assessed by the Newcastle- Ottawa Scale and random effects meta-analysis was used to compare the risk estimates between studies. Result(s): The search retrieved 3435 citations, of which 57 underwent full-text review. Eighteen studies comprising 92,218 patients met the inclusion criteria. The most common sources of bias were poor representativeness of patient cohorts, and insufficient follow up. Across the 10 studies examining mortality, AKI was associated with a significantly increased risk of death (HR 1.71, 95% CI 1.43-2.04), which progressively increased with AKI stage, although heterogeneity was high (I2 84.5%). There was also an association between AKI and ESKD (HR 5.18, 95% CI 3.14-8.53) and a non-significant increased risk of CKD (HR 5.72, 95% CI 0.62-52.67). Conclusion(s): Despite high heterogeneity between studies, AKI was associated with inferior long-term survival and an increased risk of adverse renal outcomes. Strategies to identify patients at greatest risk are required, to ensure appropriate long-term care is coordinated for t