Helicopter Emergency Medical Services attendance is associated with favourable survival outcomes in major trauma: derivation and internal validation of prediction models in a regional trauma system.
Emergency medicine journal · 2026-02-04 · Observational study
Abstract
BACKGROUND: Survival benefit of Helicopter Emergency Medical Services (HEMS) attended major trauma remains inadequately quantified across injury severity. We evaluated HEMS performance and identified predictors of survival. METHODS: Retrospective observational analysis of 3225 trauma patients attended by a regional HEMS in South-East England (2013-2022). Survival was assessed using W-statistic (Ws ) methodology stratified by probability of survival (Ps ) bands. Multivariable logistic regression identified predictors of 30-day mortality in major trauma (injury severity score (ISS) ≥15). Sub-analysis examined unexpected survival predictors and return of spontaneous circulation (ROSC) rates in traumatic cardiac arrest (TCA). RESULTS: Among 2125 patients meeting Ws analysis criteria, observed (O) 30-day survival exceeded expected (E) survival (84.7% vs 81.3%; O/E ratio 1.04), yielding adjusted Ws of 5.23 (95% CI 3.27 to 7.19), representing 5.23 excess survivors per 100 patients. Survival benefit was greatest in severely injured patients with moderate survival probability (Ps 25-45%: 3.33 excess survivors per 100, 95% CI 1.37 to 5.29). Among patients with low probability of survival (Ps <50), 38.7% survived unexpectedly; younger ages and higher presenting Glasgow Coma Scale scores were key predictors of unexpected survival. Pre-hospital emergency anaesthesia (PHEA) was independently associated with unexpected survival in this group (adjusted OR 2.01, 95% CI 1.12 to 3.72, p=0.023). TCA ROSC rates demonstrated an annual improvement (6.3% increased odds per year, 95% CI 1.02 to 1.10, p=0.002). CONCLUSION: HEMS attendance to major trauma in this regional service was associated with survival exceeding case-mix adjusted predictions, and was most pronounced in severely injured patients. PHEA was associated with survival benefit in low probability patients, supporting the value of advanced pre-hospital interventions.
Tags
Anaesthetics · Mortality & survival · Prehospital physicians · Rapid sequence intubation