A NEW retrospective study suggests that the red cell distribution width-to-platelet ratio (RPR) may help predict cardiac surgery-associated acute kidney injury (CSA-AKI), offering clinicians a potentially accessible biomarker for early risk stratification.
CSA-AKI remains a frequent and serious complication following cardiac surgery with cardiopulmonary bypass (CPB), contributing to prolonged hospital stays, increased costs, and higher mortality. Identifying patients at risk before overt renal dysfunction develops is therefore a clinical priority.
In this single-centre analysis, researchers evaluated 252 patients who underwent cardiac surgery with CPB. Participants were classified according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria into AKI (n=136) and non-AKI (n=116) groups. Baseline creatinine was defined as the last value recorded before surgery. Laboratory parameters, including complete blood counts, renal function, and hepatic function, were assessed daily for the first seven postoperative days. For patients who developed AKI, laboratory values from the day immediately preceding onset were used in the analysis.
Higher RPR Levels Linked to Increased Acute Kidney Injury Risk
RPR levels were significantly higher in the AKI group compared with the non-AKI group (14.94 versus 8.46; p<0.001). Multivariable analysis showed that elevated RPR was independently associated with CSA-AKI risk (odds ratio 1.433; 95% CI 1.158–1.774), with model assumptions satisfied.
Receiver operating characteristic (ROC) curve analysis demonstrated that RPR had strong predictive performance, ranking second only to blood urea nitrogen (BUN). The area under the curve (AUC) for RPR was 0.855, compared with 0.926 for BUN. An optimal RPR cut-off value of 11.416 was identified.
Importantly, predictive accuracy improved when RPR was combined with other biomarkers. The combination of RPR with BUN or C-reactive protein (CRP) significantly enhanced discrimination, with the triad of RPR, CRP, and BUN achieving an AUC of 0.978. The combined model was pre-specified and showed no interaction between variables.
Clinical Implications for Early Risk Stratification
However, the authors caution that the findings are limited by the study’s retrospective, single-centre design, lack of external validation, and inconsistent RPR measurement thresholds. The analysis does not establish causality.
Overall, the study indicates that RPR, particularly when integrated with conventional markers, may support early identification of patients at risk of CSA-AKI, potentially informing perioperative renal protection strategies. Larger prospective studies are needed to validate these results.
Reference
Li ZX et al. Postoperative red cell distribution width to platelet ratio is related to cardiac surgery-associated acute kidney injury. BMC Cardiovasc Disord 2026;26:178.
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