Association between physician-staffed helicopter versus ground emergency medical services and mortality for pediatric trauma patients: A retrospective nationwide cohort study

BACKGROUND: Helicopter emergency medical services’ (HEMS) effectiveness for pediatric trauma patients remains unclear. We aimed to examine the relation between HEMS and reduced mortality in pediatric trauma patients. METHODS: This retrospective cohort study utilized data from the Japan Trauma Data Bank, a national multicenter clinical trauma database. Participants were aged <18 years, admitted between 2004 and 2015, and transported from the scene to the hospital by HEMS or ground emergency medical services (GEMS). We used a standardized mortality ratio (SMR) weight method, and fitted a marginal structural model to adjust for measured confounders. The SMR weight was calculated using the estimation of the propensity scores. A logistic regression model was used with the baseline independent variables to estimate the propensity score. RESULTS: Overall, 5,947 patients were identified in our study: 453 were transported by HEMS and 5,494 by GEMS. The mean injury severity score in the HEMS group was significantly higher than that in the GEMS group17.0 (Standard deviation = 11.0) vs 12.2 (Standard deviation = 9.2), p < .001. In-hospital mortality was higher in the HEMS group than that in the GEMS group in the unadjusted analysis (3.8% vs 1.3%, respectively; p < .001). After adjusting for covariates, HEMS transport was not associated with reduced hospital mortality. (odds ratio = 0.82, 95% confidence interval = 0.42–1.58). CONCLUSIONS: HEMS was not associated with reduced mortality among pediatric trauma patients compared with GEMS in this nationwide study. Further investigation is necessary to determine who clearly benefits from HEMS as compared to GEMS.