Postoperative Red Cell Distribution Width to Platelet Ratio Is Related To Cardiac Surgery-Associated Acute Kidney Injury

Background This study aimed to investigate the predictive value of the red cell distribution width-to-platelet ratio (RPR) for cardiac surgery-associated acute kidney injury (CSA-AKI). Methods A retrospective analysis of clinical data from 252 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) was conducted. Patients were classified into AKI (n = 136) and non-AKI (n = 116) groups based on KDIGO criteria. Receiver operating characteristic (ROC) curve was used to determine the optimal cut-off value, and the area under the curve (AUC) was applied to compare predictive ability among different indices. Results Clinical outcomes revealed significantly higher RPR levels in the AKI group compared to the non-AKI group (14.94 vs. 8.46, p < 0.001), with elevated RPR independently associated with AKI risk(OR = 1.433, 95% CI: 1.158–1.774). ROC curve analysis demonstrated that RPR ranked second in predictive efficacy for CSA-AKI after blood urea nitrogen (BUN) (AUC = 0.855 vs. 0.926), with an optimal cutoff value of 11.416. Varieties’ combination analysis showed that combining RPR with BUN or C-reactive protein (CRP) significantly enhanced predictive accuracy, achieving an AUC of 0.978 for the RPR + CRP + BUN triad. The study further elucidated RPR’s pathophysiological role, integrating inflammatory and thrombotic mechanisms, potentially exacerbating renal injury through microcirculatory dysfunction and oxidative stress. However, the study is limited by its single-center retrospective design, necessitating validation through large-scale prospective trials. Conclusion RPR may serve as a potential predictor for CSA-AKI, and its integration with conventional biomarkers could inform renal protection strategies.