Association between helicopter with physician versus ground emergency medical services and survival of adults with major trauma in Japan

Abstract

Introduction: Helicopter emergency medical services with a physician (HEMS) has been provided in Japan since 2001. However, HEMS and its possible effect on outcomes for severe trauma patients have still been debated as helicopter services require expensive and limited resources. Our aim was to analyze the association between the use of helicopters with a physician versus ground services and survival among adults with serious traumatic injuries.

Methods: This multicenter prospective observational study involved 24,293 patients. All patients were older than 15 years of age, had sustained blunt or penetrating trauma and had an Injury Severity Score (ISS) higher than 15. All of the patient data were recorded between 2004 and 2011 in the Japan Trauma Data Bank, which includes data from 114 major emergency hospitals in Japan. The primary outcome was survival to discharge from hospitals. The intervention was either transport by helicopter with a physician or ground emergency services.

Results: A total of 2,090 patients in the sample were transported by helicopter, and 22,203 were transported by ground. Overall, 546 patients (26.1%) transported by helicopter died compared to 5,765 patients (26.0%) transported by ground emergency services. Patients transported by helicopter had higher ISSs than those transported by ground. In multivariable logistic regression, helicopter transport had an odds ratio (OR) for survival to discharge of 1.277 (95% confidence interval (CI), 1.049 to 1.556) after adjusting for age, sex, mechanism of injury, type of trauma, initial vital signs (including systolic blood pressure, heart rate and respiratory rate), ISS and prehospital treatment (including intubation, airway protection maneuver and intravenous fluid). In the propensity score-matched cohort, helicopter transport was associated with improved odds of survival compared to ground transport (OR, 1.446; 95% CI, 1.220 to 1.714). In conditional logistic regression, after adjusting for prehospital treatment (including intubation, airway protection maneuver and intravenous fluid), similar positive associations were observed (OR, 1.230; 95% CI, 1.017 to 1.488).

Conclusions: Among patients with major trauma in Japan, transport by helicopter with a physician may be associated with improved survival to hospital discharge compared to ground emergency services after controlling for multiple known confounders.

Figure 1

Study flow diagram. Stratification and selection of patient data retrieved from the Japan Trauma Data Bank (JTDB) covering the period from 2004 to 2011.