Abstract
BACKGROUND: Inflammation is one of the important pathophysiological characteristics of acute kidney injury (AKI) after cardiac surgery. The aim was to explore the relationship between preoperative neutrophil-to-lymphocyte ratio (NLR), a simple and cost-effective maker of inflammatory response, and AKI after cardiac surgery. Furthermore, whether the NLR affected in-hospital mortality was also investigated. METHODS: The electronic medical records of patients from January 1, 2006 to December 31, 2018 undergoing cardiac surgery were utilized. The interest outcome was AKI, defined as the criteria of Kidney Disease Improving Global Outcomes (KDIGO), and other outcomes were severe AKI (KDIGO stage ≥2) and in-hospital mortality. Logistic regression was utilized to assess the association of preoperative NLR with outcomes while adjust for potential confounders. RESULTS: Totally, 23,638 patients were included. The incidence of AKI was 27.6%. The NLR was significantly greater in patients with AKI compared to those without. As the nonlinear relationship between NLR and AKI indicated by restricted cubic spline, NLR was analyzed as a categorical variable with the cutoff value of five. Multivariate analysis demonstrated that NLR > 5 was significantly associated with an increased risk of AKI, with an odds ratio of 5.046 (95% confidence interval, 4.589 to 5.548), when compared to patients with NLR ≤ 5. Furthermore, high NLR was also an independent risk factor for severe AKI and in-hospital mortality. CONCLUSIONS: A higher preoperative NLR was increased the risk of AKI, severe AKI, and in-hospital mortality after cardiac surgery, which may be helpful for stratifying patients to develop individualized treatment.