The impact of early versus late initiation of renal replacement therapy in critical care patients with acute kidney injury: a systematic review and evidence synthesis

Background: The optimal timing of initiating renal replacement therapy (RRT) in critical illness complicated by acute kidney injury (AKI) is not clearly established. Trials completed on this topic have been marked by contradictory findings as well as quality and heterogeneity issues. Our goal was to perform a synthesis of the evidence regarding the impact of early versus late RRT in critically ill patients with AKI, focusing on the highest-quality research on this topic. Methods: A literature search using the PubMed and Embase databases was completed to identify studies involving critically ill adult patients with AKI who received hemodialysis according to early versus late/ standard criteria. The highest-quality studies were selected for meta-analysis. The primary outcome of interest was mortality at 1 month (composite of 28-and 30-day mortality). Secondary outcomes evaluated included intensive care unit (ICU) and hospital length of stay (LOS). Results: Thirty-six studies (seven randomized controlled trials, ten prospective cohorts, and nineteen retrospective cohorts) were identified for detailed evaluation. Nine studies involving 1042 patients were considered to be of high quality and were included for quantitative analysis. No survival advantage was found with early RRT among high-quality studies with an OR of 0.665 (95 % CI 0.384-1.153, p = 0.146). Subgroup analysis by reason for ICU admission (surgical/medical) or definition of early (time/biochemical) showed no evidence of survival advantage. No significant differences were observed in ICU or hospital LOS among high-quality studies. Conclusions: Our conclusion based on this evidence synthesis is that early initiation of RRT in critical illness complicated by AKI does not improve patient survival or confer reductions in ICU or hospital LOS.