Acute kidney injury after burn surgery: Preoperative neutrophil/lymphocyte ratio as a predictive factor

Background Severe inflammation and acute kidney injury (AKI) are serious adverse events after burn injuries. The neutrophil/lymphocyte ratio (NLR) is a marker of inflammation. We evaluated the independent risk factors for postoperative AKI, including NLR, in burn-injured patients. Methods The preoperative, intraoperative, and postoperative variables of 473 burn-injured patients were collected. The risk factors for AKI after burn surgery were evaluated using univariate and multivariate logistic regression analyses. The receiver operating characteristic (ROC) curve analysis of preoperative NLR was performed. The 3-month mortality after surgery was also compared between AKI and non-AKI groups using Kaplan-Meier analysis with a log-rank test. Results Postoperative AKI occurred in 71 of 473 (15.0%) burn patients. The total body surface area burned (odds ratio (OR), 1.013; 95% confidence interval (CI), 1.001-1.026; P = 0.037), inhalation injury (OR, 1.821; 95% CI, 1.008-3.292; P = 0.047), and preoperative NLR (OR, 1.094; 95% CI, 1.064-1.125; P < 0.001) were risk factors for AKI after surgery. The area under the ROC curve was 0.767, with an optimal cut-off value of 11.7. Moreover, the 3-month mortality after surgery was significantly higher in the AKI group than in the non-AKI group (49.3% vs 14.9%, P < 0.001). Conclusion Total body surface area burned, inhalation injury, and preoperative NLR are risk factors for AKI after burn surgery, which is associated with early postoperative mortality. Preoperative NLR can provide useful information for the early detection of postoperative AKI and subsequent mortality in burn-injured patients.