Background: Several studies have shown that the neutrophil-lymphocyte ratio (NLR) predicts outcomes in organ transplantation patients. This study aimed to investigate the association between high NLR and 6-month mortality after lung transplantation (LTx).

Methods: We retrospectively reviewed 282 lung transplantation recipients between October 2012 and August 2020. NLR was calculated before LTx, postoperative day (POD) 1, 3, 7 and 28. We categorized patients into two groups according to 6-month mortality. Multivariate logistic regression, Receiver operating characteristic (ROC) curve and Kaplan-Meier analysis were used to analyze outcomes.

Result: The mean age was 54.2±12.3 years. Of 282 patients, 68 patients (24.1%) died within six months after LTx. The two groups did not differ in NLR on POD 1, 3, and 7. The mean preoperative(Preop) NLR and NLR on POD 28 were higher in non-survivors than in 6-month survivors (13.9±15.6 vs. 8.2±8.2, p-value = 0.005, 21.0±18.0 vs. 11.0±10.6, p-value<0.001, respectively). Univariate analysis revealed seven factors that significantly associated mortality: age, Preop NLR, NLR on POD 28, Preop albumin, and duration of extracorporeal membrane oxygenation before LTx. Multivariate analysis showed that only elevated NLR on POD 28 was associated with six-month mortality (odds ratio, 1.05 [1.02-1.07], p-value<0.001). Patients with over 9.20 NLR on POD 28, derived through ROC (Area Under Curve, 0.698; 95% confidence interval, 0.62-0.78; sensitivity, 71.4%; specificity, 59.8%), showed lower survival on Kaplan-Meier analysis (p-value<0.001, Log-rank).

Conclusion: Patients with elevated NLR at POD 28 after lung transplantation showed poor short-term survival.