Initial neutrophil and lymphocyte ratio as a predictor of mortality and ICU admission after major trauma

Introduction: The neutrophil-to-lymphocyte ratio (NLR) has been proposed as a marker of systemic inflammation in major trauma patients that is associated with in-hospital mortality. We aimed to determine the discriminative ability of initial NLR as a predictor of outcomes following major trauma. Methods: This was a registry-based cohort study involving all major trauma patients meeting criteria for inclusion into the Alfred Health Trauma Registry who presented directly from the scene of injury over a 24-month period (January 2018 to December 2019). The initial NLR was calculated for each patient and was compared against the Shock Index (SI), lactate and Revised Trauma Score (RTS). Outcomes observed were mortality at hospital discharge and intensive care unit (ICU) admission. We assessed the predictive capacity of each test using the receiver operating characteristic (ROC) curve and performed area under the ROC curve (AUROC) analysis to compare their performance. Results: Data were extracted for 1687 major trauma patients, of which 72% were male, the median age was 49 years (IQR 31-68) and most (90%) of patients presented after a blunt mechanism of injury. In-hospital mortality occurred in 165 (9.77%) patients, and 725 (42.92%) patients required ICU admission. The median NLR was 6.84 (IQR 3.89-11.52). Initial NLR performed poorly with an AUROC of 0.46 (95% confidence interval (CI): 0.40-0.52) for prediction of mortality and AUROC of 0.53 (95% CI: 0.50-0.56) for prediction of ICU admission. The AUROCs of initial NLR for both mortality at hospital discharge and ICU admission were significantly lower than SI, lactate and RTS. Conclusion: Initial NLR was not predictive of outcomes in major trauma. NLR at other time-points may provide better predictive capacity for outcomes.