WASHINGTON, D.C. – In a study that included data on more than 200,000 adults with serious injuries admitted to level I or II trauma centers, transport by helicopter compared with ground emergency medical services was associated with improved survival to hospital discharge, according to a study in the April 18 issue of JAMA, a theme issue on comparative effectiveness research.
Adil H. Haider, M.D., M.P.H., F.A.C.S., of the Johns Hopkins University School of Medicine, Baltimore, presented the findings of the study at a JAMA media briefing at the National Press Club.
"Trauma remains the leading cause of death and disability among young people around the world. In the United States, more than 50 million people are injured per year, resulting in approximately 169,000 annual deaths and a life-time cost of $406 billion," according to background information in the article. The use of helicopter emergency medical services (EMS) and its possible effect on outcomes for traumatically injured patients has been the subject of debate. "Because helicopter transport is a limited and expensive resource, a methodologically rigorous investigation of its effectiveness compared with ground EMS is warranted."
Dr. Haider and colleagues conducted a study to compare the association between the use of helicopter vs. ground EMS and survival among adults with traumatic injuries. The study included 223,475 patients older than 15 years who had an injury severity score that was defined as major trauma, and sustaining blunt or penetrating trauma that required transport to U.S. level I or II trauma centers. The patients data were recorded in the 2007-2009 versions of the American College of Surgeons National Trauma Data Bank. The measured outcomes included survival to hospital discharge and discharge disposition.
Of the study population, 61,909 patients were transported by helicopter and 161,566 by ground to trauma centers. Unadjusted mortality was higher for those transported by helicopter (n = 7,813; 12.6 percent) than those by ground (n = 17,775; 11 percent); however, a higher proportion of both level I and level II patients transported by helicopter had higher Injury Severity Scores. After further analyses and controlling for multiple known confounders (factors that can influence outcomes), for patients transported to level I trauma centers, helicopter transport was associated with a 16 percent improved odds of survival compared with ground transport (absolute risk reduction, 1.5 percent). For patients transported to level II trauma centers, helicopter transport was associated with a 15 percent improved odds of survival (absolute risk reduction, 1.4 percent). "Thus, for patients transported to level I trauma centers by helicopter, 65 patients would need to be transported to save 1 life; for patients transported to level II trauma centers, the number needed to treat is 69," the authors write.
When considering patient disposition following hospital discharge, results suggest a higher injury severity in the helicopter group than in the ground transport group. At level I centers, fewer patients in the helicopter groups were discharged home without services (47.6 percent) than in the ground transport group (57.3 percent). A higher proportion of those transported by helicopter to level I trauma centers were discharged to rehabilitation (18.2 percent vs. 12.7 percent in ground transport group) and to intermediate facilities (9.3 percent vs. 6.5 percent, respectively). Patients transported by ground services were more likely to be discharged from level I centers to a nursing home.
The authors note that it is not clear which aspect of helicopter transport is responsible for the mortality benefit in this highly stratified sample. "Future studies should investigate specific components of helicopter EMS such as prehospital interventions, total prehospital time, crew configuration, and distance as factors that may in part or whole explain the benefit of helicopter EMS for adults with major trauma because understanding the effectiveness of each may help determine which patients benefit most from this resource."
The researchers add that to date, the development and use of effective prehospital triage tools that can identify adults with a high injury severity score have remained elusive. "Future studies should focus on efficient and user-friendly prehospital assessment tools to properly identify injured adults who will be the most likely to benefit from helicopter transport."