A Comparison of the Association of Helicopter and Ground Ambulance Transport with the Outcome of Injury in Trauma Patients Transported from the Scene

INTRODUCTION: Comprehensive emergency medical services and helicopter aeromedical transport systems have been developed based on the principle that early definitive care improves outcome. The purpose of this study was to compare outcomes between patients transported by helicopter and those transported by ground. METHODS: Data were obtained from the North Carolina Trauma Registry for the period between 1987 and 1993 on all patients transported by helicopter and ground admitted to one of the eight state designated trauma centers. Study patients included only those who were transported directly from the scene of injury to the trauma center (interhospital transfers were excluded). Mortality (outcome) was compared after patient stratification by injury severity and transport time, using Cochran-Mantel-Haenszel statistics and logistic regression-derived probabilities of survival. RESULTS: One thousand three hundred forty-six patients (7.3% of the total) were transported from scene to trauma center by helicopter and 17,144 were transported by ground. In patients transported by helicopter, the mean Trauma Score was lower (12 +/- 3.6) versus 14.3 +/- 3.6 (p < 0.001) and the mean Injury Severity Score was higher (17 +/- 11.1) versus 10.8 +/- 8.4 (p < 0.001). A trend toward increased survival was observed among patients transported by helicopter with a higher Injury Severity Score. Statistical significance was achieved only for patients with a Trauma Score between 5 and 12 and Injury Severity Score between 21 and 30. CONCLUSION: The large majority of trauma patients transported by both helicopter and ground ambulance have low injury severity measures. Outcomes were not uniformly better among patients transported by helicopter. Only a very small subset of patients transported by helicopter appear to have any chance of improved survival based on their helicopter transport. This study suggests that further effort should be expended to try to better identify patients who may benefit from this expensive and risky mode of transport.