Helicopter emergency medical service (HEMS) transport of trauma patients is costly and of unproven benefit. Recent retrospective studies fail to control for crew expertise and therefore compare highly trained advance life support with less-trained basic life support crews. The purpose of our study was to compare HEMS with ground, interfacility transport while controlling for crew training. We hypothesized that patients transported by HEMS would experience shorter interhospital transport time and reduced mortality.
Our National Trauma Registry of the American College of Surgeons database was retrospectively queried to identify consecutive interfacility, hospital transfers (January 1, 2008, to November 1, 2012) to our Level I trauma center. Transfers were stratified by transportation vehicle (i.e., HEMS vs. ground transport). Cohorts were compared across standard demographic and clinical variables using univariate analysis. Multivariate logistic regression was performed to determine the association of these variables with mortality.
The HEMS (n = 2,190) and ground (n = 223) cohorts were well matched overall, with no significant differences for demographics, injury severity, physiology, hospital length of stay, or complications. Median (interquartile range) time to definitive care was significantly lower for HEMS (150  minutes vs. 255  minutes, p < 0.001), without change in mortality (9.0% vs. 8.1%, p = 0.71). Multivariate logistic regression did not identify an association between transport mode and mortality.
Despite faster interfacility transport times, HEMS offered no mortality benefit compared with ground when crew expertise was controlled for, contradicting recent large, retrospective National Trauma Data Bank studies. Our study may represent the best approximation of a prospective study by focusing on patients deemed worthy of HEMS by referring providers. Although HEMS may seem intuitively beneficial for time-dependent injuries, larger studies with a similar methodology are warranted to justify the cost and risk of HEMS and identify subsets of patients who may benefit.
Prognostic/epidemiologic study, level III.