Dissecting the Albumin Assumption: Can Albumin Reduce Acute Kidney Injury after Cardiac Surgery Compared with Crystalloids? A Systematic Review and Meta-analysis

Abstract Introduction: Acute kidney injury (AKI) is a common and serious complication after cardiac surgery. Albumin has been proposed as a superior fluid for perioperative management compared to crystalloids. We aimed to evaluate whether albumin reduces the incidence of AKI compared to crystalloid solutions in patients undergoing cardiac surgery. The need for renal replacement therapy (RRT) was assessed as a secondary outcome. Materials and Methods: A systematic search was performed on PubMed, ScienceDirect, and Scopus. Eligible studies were randomized controlled trials (RCTs) comparing albumin to crystalloids in adult or pediatric cardiac surgery patients and reporting AKI based on standardized criteria. Risk of bias (RoB) was assessed using the Cochrane RoB 2.0 tool. Meta-analysis was performed, calculating risk ratios (RRs) with 95% confidence intervals (CIs) and applying random- or fixed-effects models depending on heterogeneity. Results: Six RCTs, including 2465 patients, were analyzed. No significant difference in AKI incidence was found between albumin and crystalloid groups (RR: 0.97, 95% CI: 0.79–1.18, P = 0.74). Subgroup analysis showed no benefit when albumin was used as a priming solution (RR: 1.06, 95% CI: 0.79–1.43), while a benefit was observed in off-pump surgery in a single study. No significant difference in RRT requirement was observed (RR: 1.75, 95% CI: 0.52–5.97, P = 0.37). Conclusion: This meta-analysis provides no evidence that albumin reduces the incidence of AKI, compared to crystalloids in cardiac surgery. Crystalloids remain an appropriate first-line choice, while future large-scale RCTs are needed to clarify whether certain patient subgroups may benefit from albumin.