Predictive Value of C-reactive Protein/Albumin Ratio and Neutrophil/Lymphocyte Ratio in Elderly Patients With Acute Kidney Injury Following On-pump Coronary Artery Bypass Graft

AIM: This study intended to investigate the predictive value of C-reactive protein (CRP)/albumin ratio (CAR) and neutrophil/lymphocyte ratio (NLR) in elderly patients with acute kidney injury (AKI) following on-pump coronary artery bypass graft (CABG). METHODS: The clinical information of elderly patients undergoing on-pump CABG admitted to Taizhou People’s Hospital was collected for retrospective analysis (n = 150). The patients were divided into two groups based on their postoperative AKI status: injury group (n = 58, with AKI) and non-injury group (n = 92, without AKI). All patients with postoperative AKI were further divided into three groups based on AKI stage: stage 1 group (n = 40), stage 2 group (n = 12), and stage 3 group (n = 6). The CAR and NLR were calculated. Multivariate logistic regression analysis was utilized to explore the risk factors for AKI after on-pump CABG in elderly patients. Receiver operating characteristic (ROC) curve analysis was conducted to predict their diagnostic utility in AKI. RESULTS: Compared with the non-injury group, the injury group exhibited reduced lymphocyte count (p < 0.001) and higher European System for Cardiac Operative Risk Evaluation II (EuroSCORE II) score, cardiopulmonary bypass (CPB) time, NLR, CRP, and CAR (p = 0.006, 0.002, <0.001, <0.001, and <0.001, respectively). Multivariate logistic regression analysis showed that CPB time (p = 0.005, odds ratio [OR] = 1.034, 95% confidence interval [CI] = 1.010–1.058), NLR (p = 0.003, OR = 1.476, 95% CI = 1.139–1.911), and CAR (p < 0.001, OR = 4.460, 95% CI = 2.237–8.890) were the independent influencing factors of AKI in elderly patients after on-pump CABG. The area under the curve (AUC) of CPB time, NLR, CAR, and the combination of NLR and CAR were 0.650, 0.787, 0.790, and 0.838, respectively. DeLong test demonstrated that the combined model incorporating NLR and CAR had significantly greater predictive performance than models using CAR alone (p = 0.011), NLR alone (p = 0.008), and CPB time alone (p = 0.001). Compared to stages 1 and 2, stage 3 patients had significantly higher EuroSCORE II scores (p < 0.05). CRP and CAR levels and age of patients were significantly higher in stage 3 than in stage 1 (p < 0.05), but the difference was not statistically significant compared to stage 2. CONCLUSIONS: NLR, CAR, and CPB time are identified as independent predictors of AKI in elderly patients undergoing on-pump CABG. The combined use of NLR and CAR demonstrates superior predictive performance for postoperative AKI compared with either indicator alone.