The association between helicopter emergency medical services and early casualty survival: A nationwide study

Background Helicopter emergency medical services (HEMS) allow for shorter transport duration in long-distance evacuations and facilitate advanced en-route medical care access. Studies comparing HEMS with ground emergency medical services (GEMS), including the outcome of prehospital mortality, are lacking. Objective This study aimed to evaluate the association between HEMS and early mortality in Israel. Setting A retrospective cohort study was conducted of the cross-referenced Israel Defense Forces Trauma Registry and Israel National Trauma Registry databases. Outcome measures and analysis Univariable logistic regression was used to assess the association between HEMS and early mortality, defined as mortality within 1 day of the injury. Regression analysis was further performed stratifying by event type (military or civilian) or type of injury (penetrating or nonpenetrating). Results A total of 2344 casualties were included in the study, of whom 756 (32.3%) were evacuated by air. Early mortality rates were 90/1588 (5.7%) and 37/756 (4.9%) in GEMS and HEMS groups, respectively. Regression analysis found no significant analysis between HEMS and early mortality [OR, 0.86 (95% CI, 0.57-1.26)]. Stratified by event type, a nonsignificant association between HEMS and early mortality was demonstrated for combat [OR, 1.69 (95% CI, 0.79-3.92)] and noncombat [OR, 0.73 (95% CI, 0.4-1.25)] events. HEMS was associated with decreased early mortality among casualties with a penetrating injury [OR, 0.59 (95% CI, 0.34-0.98)] but not associated with early mortality among casualties with a nonpenetrating injury [OR, 0.84 (95% CI, 0.43-1.52)]. Conclusion HEMS was not associated with a decrease in early mortality among trauma casualties in this study encompassing the prehospital and hospital scenes. There was a positive trend and a decrease in mortality from penetrating injuries. Further research to ascertain which casualties benefit from HEMS is warranted and will allow for more precise use of this expensive resource.