Predictive value of neutrophil to lymphocyte ratio on acute kidney injury after on-pump coronary artery bypass: a retrospective, single-center study.

Objective: To investigate the predictive value of preoperative neutrophil to lymphocyte ratio (NLR) on acute kidney injury (AKI) after on-pump coronary artery bypass (ONCAB).

Methods: Patients who underwent elective ONCAB for coronary heart disease were included. NLR was calculated according to the results of preoperative routine blood test, patients were divided into non-AKI and AKI groups, and the differences in clinical baseline data between the two groups were compared.

Results: A total of 154 patients were included in this study, including 57 (37%) with postoperative AKI and 97 (63%) without AKI. Compared with the patients in non-AKI group, those in AKI group had higher NLR (2.63 (1.83, 3.505) vs. 2.06 (1.7, 2.56), p = 0.002), higher serum creatinine (78 (67, 98.5) vs. 70.9 ± 16.8 umol/L, p < 0.001), longer cardiopulmonary bypass time, and longer aortic cross clamp time. After dividing patient into tertiles based on NLR, those with higher NLR had higher risk of postoperative AKI than those with lower NLR (30% vs. 25% vs. 55.8%, p for trend = 0.003). Patients in Tertile2 and Tertile3 had higher NLR compared to those in Tertile1 (p < 0.05); multivariate logistic regression analysis showed patients with elevated preoperative NLR and blood creatinine had higher risk of postoperative AKI. ROC curve showed that patients' preoperative NLR combined with blood creatinine had better predictive value for postoperative AKI.

Conclusion: Elevated preoperative NLR is associated with AKI after ONCAB, and had prognostic utility independent of other recognized risk factors.