# The 24-Hour Leukocyte Gap as a novel predictor for sepsis in adult severe blunt trauma

## TL;DR

This study introduces a new immune parameter, the 24-hour leukocyte gap, which can predict sepsis risk in severely injured trauma patients using routine blood tests.

## Contribution

The study introduces the 24-hour leukocyte gap as a novel dynamic immune parameter for predicting sepsis in trauma patients.

## Key findings

- The 24-hour leukocyte gap was found to be an independent predictor of sepsis in trauma patients.
- A 24-hour leukocyte gap greater than 10 was associated with increased septic shock and mortality rates.
- The parameter uses routine lab measurements, making it feasible for clinical use.

## Abstract

Predicting the likelihood of developing sepsis following severe trauma remains a challenge. As the incidence of sepsis is associated with early post-traumatic episodes of both leukopenia and leukocytosis, various static markers have been trailed in order to help identify and risk stratify patients, nevertheless these have not proven reliable. The goal of this study was to develop and test a novel dynamic immune parameter that could help predict the risk of developing sepsis, the 24-hour leukocyte gap (24 h-LCG), defined as the difference between blood leukocyte numbers on admission and after 24 h.

A single centre prospective trauma registry was used in order to identify adults who had sustained severe trauma, defined as an Injury Severity Score (ISS) ≥ 9. Patients were stratified into groups based on whether sepsis had occurred. Multivariable regression analysis was performed and utilised in order to analyse predictive immune parameters for sepsis, septic shock and mortality.

1,592 eligible patients were identified, of whom 251 subsequently developed sepsis. Patients diagnosed with sepsis were younger (p < 0.002), presented with a higher ISS and had worse hemodynamic parameters on admission (p < 0.001). The 24 h-LCG was found to be an independent immunological predictive parameter for sepsis by the multivariable analysis. Moreover, a 24 h-LCG greater than 10, was associated with a significantly increased incidence of septic shock (12.4% vs. 4.3%, p < 0.001) and mortality 6.0 vs. 2.7%, p = 0.036), compared with the control group.

This study is the first to demonstrate that 24-hour LCG has clinical potential as an independent and early predictive parameter of sepsis in severely injured trauma patients. Furthermore, its feasibility and clinical translatability comes from the use of routine laboratory measurements, namely leukocytes. Its potential lies in assisting future clinical decision making, particularly with regard to the timing of surgery in trauma patients.