Association of White Blood Cell Subtypes and Derived Ratios with a Mortality Outcome in Adult Patients with Polytrauma

Background. After trauma, the subtypes of white blood cells (WBCs) in circulation and the derived neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) may undergo relative changes and reflect the patients’ immune-inflammatory status and outcome. This retrospective study was designed to investigate the relationship between these variables and the mortality outcomes in adult patients with polytrauma, which is defined as an abbreviated injury scale (AIS) score ≥ 3 in two or more different body regions. Methods. A comparison of the expression of subtypes of WBCs, NLR, MLR, and PLR upon arrival to the emergency department was performed in selected propensity score-matched patient cohorts created from 479 adult patients with polytrauma between 1 January 2015 and 31 December 2019. A multivariate logistic regression analysis was used to identify the independent risk factors for mortality. Results. There were no significant differences in monocyte, neutrophil, and platelet counts, as well as in MLR, NLR, and PLR, between deceased (n = 118) and surviving (n = 361) patients. In the propensity score-matched patient cohorts, which showed no significant differences in sex, age, comorbidities, and injury severity, deceased patients had significantly higher lymphocyte counts than survivors (2214 ± 1372 vs. 1807 ± 1162 [106/L], respectively, p = 0.036). In addition, the multivariate logistic regression analysis revealed that the lymphocyte count (OR, 1.0; 95% confidence interval [CI], 1.00–1.06; p = 0.043) was a significant independent risk factor for mortality in these patients. Conclusions. This study revealed that there was no significant difference in the counts of monocytes, neutrophils, and platelets, as well as in MLR, NLR, and PLR, between deceased and surviving patients with polytrauma. However, a significantly higher lymphocyte count may be associated with a worse mortality.