Mortality following helicopter versus ground transport of injured children.

INTRODUCTION: Injured children may be transported to trauma centers by helicopter air ambulance (HAA); however, a benefit in outcomes to this expensive resource has not been consistently shown in the literature and there is concern that HAA is over-utilized. A study that adequately controls for selection biases in transport mode is needed to determine which injured children benefit from HAA. The purpose of this study was to determine if HAA impacts mortality differently in minimally and severely injured children and if there are predictors of over-triage of HAA in children that can be identified.

METHODS: Children ≤18 years of age transported by HAA or ground ambulance (GA) from scene to a trauma center were identified from the 2010-2011 National Trauma Data Bank. Analysis was stratified by Injury Severity Score (ISS) into low ISS (≤15) and high ISS (>15) groups. Following propensity score matching of HAA to GA patients, conditional multivariable logistic regression was performed to determine if transport mode independently impacted mortality in each stratum. Rates and predictors of over-triage of HAA were also determined.

RESULTS: Transport by HAA occurred in 8218 children (5574 low ISS, 2644 high ISS) and by GA in 35305 (30506 low ISS, 4799 high ISS). Overall mortality was greater in HAA patients (4.0 vs 1.4%, p<0.001). After propensity score matching, mortality was equivalent between HAA and GA for low ISS patients (0.2 vs 0.2%, p=0.82) but, for high ISS patients, mortality was lower in HAA (9.0 vs 11.1% p=0.014). On multivariable analysis, HAA was associated with decreased mortality in high ISS patients (OR=0.66, p=0.017) but not in low ISS patients (OR=1.13, p=0.73). Discharge within 24h of HAA transport occurred in 36.5% of low ISS patients versus 7.4% high ISS patients (p<0.001).

CONCLUSIONS: Based on a national cohort adjusted for nonrandom assignment of transport mode, a survival benefit to HAA transport exists only for severely injured children with ISS >15. Many children with minor injuries are transported by helicopter despite frequent dismissal within 24h and no mortality benefit.