Longitudinal analysis of neutrophil-to-lymphocyte ratio over time after major trauma

Abstract

Background The neutrophil-to-lymphocyte ratio has been proposed as a marker of systemic inflammation in major trauma patients that is associated with in-hospital mortality. However, the initial neutrophil-to-lymphocyte ratio does not appear to be predictive of in-hospital mortality. The aim of this study is to determine the discriminative ability of the neutrophil-to-lymphocyte ratio profile over 48 h as a predictor of in-hospital mortality following major trauma. Methods This was a case-control study involving all major trauma patients meeting the criteria for inclusion into the Alfred Health Trauma Registry who presented directly from the scene of injury over a 24-month period. Patients were then divided into two groups, cases being major trauma patients who died at hospital discharge and controls being patients who survived. We extracted data for Day 0, Day 1 and Day 2 neutrophil-to-lymphocyte ratio values for each patient. The primary outcome was mortality at hospital discharge. Results Data were extracted for 1689 major trauma patients, of which 72% were male, the median age was 49 years (IQR 31–68) and most (90%) patients presented after a blunt mechanism of injury. There were 165 cases that were compared to 1524 controls. Patients who died were older ( p < 0.001), and had higher injury severity scores ( p < 0.001) and lower revised trauma scores ( p < 0.001). Analysis of response profiles demonstrated a significant difference between the trajectories of the neutrophil-to-lymphocyte ratio over time ( p < 0.001). Conclusions The profile of neutrophil-to-lymphocyte ratio over 48 h after injury shows promise as a prognostic tool in trauma and warrants further investigation.