Association between Neutrophil-to-Lymphocyte Ratio and Survival of Critically Ill Newborns: A Propensity Score-Matched Analysis of the MIMIC-III Database

Introduction: The neutrophil-to-lymphocyte ratio (NLR) is an easily accessible biological marker that has attracted attention as potential markers of morbidity and mortality in various diseases. The present study aimed to evaluate the performance of initial NLR in assessing the prognosis of patients in the neonatal intensive care unit (NICU).

Materials and Methods: The study was based on the Medical Information Mart for Intensive Care (MIMIC) III database. The participants were divided into survivor group and dead group according to the clinical outcome of 28 days after admission. Propensity-score matching was used to reduce the imbalance. Survival analysis was performed to determine whether the initial NLR was associated with 28-day mortality. Receiver operating characteristic (ROC) curve was plotted, the efficiency of initial NLR for predicting 28-day mortality was evaluated by the area under ROC curve (AUC).

Results: A total of 6,442 patients were included. 47 survived patients and 48 dead patients had similar propensity scores and were included in the analyses. After matching, the initial NLR in the dead group and survivor group was 0.38 (0.24-0.68) and 0.09 (0.04-0.13) with a significant difference (P＜0.05). ROC curve analysis showed that the AUC of initial NLR predicting prognosis of patients was 0.923 (0.850-0.968). Survival analysis showed that Quartile 4 of initial NLR was significant risk factors for predicting 28-day mortality compared to that of Quartile 1 with a hazard ratio (HR) of 16.25 (95% CI, 6.76-39.06, P < 0.05).

Conclusions: The initial NLR measured at NICU admission was independently associated with 28-day mortality.