Background: Helicopter emergency medical services (HEMS) are frequently used to transport injured children, despite unclear evidence of benefit. The study objective was to evaluate the association of HEMS compared with ground emergency medical services (GEMS) transport with outcomes in a national sample of pediatric trauma patients.
Methods: Patients 15 years or younger undergoing scene transport by HEMS or GEMS in the National Trauma Data Bank from 2007 to 2012 were included. Propensity score matching was used to match HEMS and GEMS patients for likelihood of HEMS transport based on demographics, prehospital physiology and time, injury severity, and geographic region. Absolute standardized differences of less than 0.1 indicated adequate covariate balance between groups after matching. The primary outcome was in-hospital survival, while the secondary outcome was discharge disposition in survivors. Conditional logistic regression determined the association between HEMS versus GEMS transport with outcomes while controlling for demographics, admission physiology, injury severity, nonaccidental trauma, and in-hospital complications not accounted for in the propensity score. Subgroup analysis was performed in patients with a transport time of greater than 15 minutes to capture patients with the potential for HEMS transport.
Results: A total of 25,700 HEMS/GEMS pairs were matched from 166,594 patients. Groups were well matched, with all propensity score variables having absolute standardized differences of less than 0.1. In matched patients, HEMS was associated with a 72% increase in odds of survival compared with GEMS (adjusted odds ratio, 1.72; 95% confidence interval, 1.26-2.36; p < 0.01). Transport mode was not associated with discharge disposition (p = 0.47). Subgroup analysis included 17,657 HEMS/GEMS pairs. HEMS was again associated with a significant increase in odds of survival (adjusted odds ratio, 1.81; 95% confidence interval, 1.24-2.65; p < 0.01), while transport mode was not associated with discharge disposition (p = 0.58).
Conclusion: Scene transport by HEMS was associated with improved odds of survival compared with GEMS in pediatric trauma patients. Further study is warranted to understand the underlying mechanisms and develop specific triage criteria for HEMS transport in this population.
Level of evidence: Therapeutic study, level III.