A socioeconomic equity measured by Indices of Multiple Deprivation for HEMS-attended major trauma in South East England: heterogenous effects in severe traumatic brain injury

Background Healthcare inequalities persist across socioeconomic gradients with deprived populations experiencing higher trauma mortality. This study aimed to determine whether 30-day mortality differs across socioeconomic deprivation quintiles in Helicopter Emergency Medical Service (HEMS) attended major trauma and to assess equity of intervention delivery and operational response. Methods Retrospective service evaluation cohort study of consecutive HEMS-attended major trauma patients (Injury Severity Score (ISS)>15) by Air Ambulance Charity Kent Surrey and Sussex (July 2013–February 2022). Indices of Multiple Deprivation quintiles derived from preassigned Lower Layer Super Output Area (LSOA) at incident location rather than patient residential address were examined alongside mortality outcomes. The primary outcome was 30-day mortality across socioeconomic quintiles (Q), with prespecified subgroups including traumatic haemorrhage and traumatic brain injury (TBI). Geospatial analysis and multivariable logistic regression were performed. Results Among 1752 major trauma patients (median ISS 27, IQR 21–36) geospatial analysis identified missions in 1190 LSOA codes (10.5% of region), with clustering in areas of moderate deprivation. 30-day mortality showed no socioeconomic gradient: 17% (95% CI 12% to 25%) in Q1 vs 21% (95% CI 17% to 25%) in Q5, p=0.861. Multivariable logistic regression confirmed no independent association between deprivation and mortality (adjusted OR per quintile increase 1.01, 95% CI 0.92 to 1.11, p=0.800). Secondary outcomes demonstrated equitable service provision with prehospital emergency anaesthesia 37–43% (p=0.667), blood transfusion 8–13% (p=0.321) and night operations 28–41% (p=0.124). Exploratory subgroup analysis identified a significant Glasgow Coma Scale×deprivation interaction in TBI (p=0.003), with possible age-dependent variations warranting further investigation. Conclusions Equitable 30-day mortality outcomes were achieved across socioeconomic quintiles within the operational region examined. A regional HEMS may mitigate health inequalities in major trauma, though complete equity requires addressing broader social determinants of health.