Predictive value of pre-operative serum uric acid on acute kidney injury after cardiac surgery

Abstract

Objective To investigate the predictive value of pre-operative serum uric acid level for acute kidney injury (AKI) after cardiopulmonary bypass surgery. Methods A retrospective analysis was made on 198 patients who undergone cardiopulmonary bypass surgery from March to August 2017 in LiHuiLi Hospital of Ningbo Medical Center. The patients were divided into AKI group and control group according to whether AKI occurred after operation. The clinical data were firstly screened by single factor analysis, and the significant variables were analyzed by multiple factor regression analysis. The receiver operating characteristic (ROC) curve was used to analyze the predictive value of preoperative serum uric acid level on postoperative AKI. Results A total of 50 patients (25.3%) had postoperative AKI, 5 of them (2.5%) required continuous renal replacement therapy (CRRT). The preoperative serum uric acid levels of AKI patients and non AKI patients were (488.91±105.52) μmol/L and (306.36±69.81) μmol/L respectively, and the difference was statistically significant (t=-8.294, P=0.036). Multiple logistic regression analysis showed that, after adjusted for age, comorbidities (hypertension, diabetes), NYHA classification≥3, cardiopulmonary bypass time> 100 min and blocking time> 60 min, the risk of AKI was significantly higher in patient with preoperative serum uric acid level> 357 μmol/L (OR: 9.074, 95%CI: 1.563-23.783, P=0.021). The area under the curve of ROC was 0.935 (95%CI: 0.877-0.993, P=0.000). The cutoff value of uric acid was 355.5 μmol/L, with a sensitivity of 95.5% and a specificity of 81.2%. Conclusions Preoperative serum uric acid level has a good predictive value for AKI after cardiopulmonary bypass surgery. Key words: Uric acid; Extracorporeal circulation; Cardiac surgery; Acute kidney injury