Impact of Early Initiation of Renal Replacement Therapy on Renal Recovery and Mortality in Critically Ill Patients with Acute Kidney Injury: A Prospective Cohort Study

Background/Objectives: Optimal timing to initiate renal replacement therapy (RRT) in critically ill patients with acute kidney injury (AKI) remains uncertain. This study evaluated the impact of early RRT initiation (<24 h after severe AKI diagnosis) on renal recovery and mortality in intensive care unit (ICU) patients. Methods: This prospective cohort included 119 patients with dialysis-requiring AKI admitted to two ICUs between December 2022 and December 2024. Patients were categorized according to RRT initiation timing (early < 24 h or delayed >24 h). Mortality (at 20, 30, and 76 days) and renal recovery (at 3, 10, and 30 days) were assessed using Kaplan–Meier curves and a log-rank test. Moreover, multivariate logistic regression was performed to identify factors associated with renal recovery. Results: Early RRT was initiated in 39 (32.8%) patients, and delayed RRT was initiated in 80 (67.2%). The early group had higher clinical severity (SOFA: 10 vs. 7; p = 0.016). Mortality did not differ between the groups (log-rank p = 0.396, 0.742, and 0.932 at 20, 30, and 76 days, respectively). However, early renal recovery (within 3 days) was more frequent in the early group (51.3% vs. 27.5%; p = 0.010), and early RRT was an independent predictor of this outcome (OR 3.26; 95% CI: 1.37–7.75 p = 0.008). Conclusions: Early RRT did not reduce mortality but was associated with improved early renal recovery in critically ill patients with AKI.