Objective: To determine the effect of aeromedical transport on trauma mortality when accounting for geographic factors.
Background: The existing literature on the mortality benefit of aeromedical transport on trauma mortality is controversial. Studies examining patient and injury characteristics find higher mortality, whereas studies measuring injury severity find a protective effect. Previous studies have not adjusted for the time and distance that would have been traveled had a helicopter not been used.
Methods: Retrospective analysis of an institutional trauma registry. We compared mortality among adult patients (≥15 years) transported from the scene of injury to our level I trauma center by air or ground (January 1, 2000-December 31, 2010) using univariate comparisons and multivariable logistic regression. Regression models were constructed to incrementally account for patient demographics and injury mechanism, followed by injury severity, and, finally, by network bands for drive time and roadway distance as predicted by geographic information systems.
Results: Of 4522 eligible patients, 1583 (35%) were transported by air. Patients transported by air had higher unadjusted mortality (4.1% vs 1.9%, P < 0.05). In multivariable modeling, including patient demographics and type of injury, helicopter transport predicted higher mortality than ground transport (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.2-4.0). After adding validated injury severity measures to the model, helicopter transport predicted lower mortality (OR 0.7, 95% CI 0.3-0.9). Finally, including geographic covariates found that helicopter transport was not associated with mortality (OR 1.1, 95% CI 0.6-2.3).
Conclusions: Helicopter transport does not impart a survival benefit for trauma patients when geographic considerations are taken into account.