Emergency medical services/original researchCost-Effectiveness of Helicopter Versus Ground Emergency Medical Services for Trauma Scene Transport in the United States
Introduction
Trauma is the leading cause of death for US residents aged 1 to 44 years, is the most common cause of years of life lost for those younger than 65 years,1 and exacts $406 billion per year in costs, more than heart disease or cancer.2, 3 Survival after trauma is improved by timely transport to a trauma center for severely injured patients.4 Helicopter emergency medical services (EMS) offers faster transport than ground EMS for patients injured far from trauma centers and is considered a preferred means of transport for critically injured patients.5 Approximately 27% of US residents are dependent on helicopter transport to access Level I or II trauma center care within the “golden hour” from injury to emergency department (ED) arrival.6 However, there are conflicting data to support routine use for scene transport. Most studies have concluded that helicopter transport was associated with improved survival,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 whereas others showed no difference.24, 25, 26, 27, 28, 29, 30 These studies have methodological limitations and selection bias, missing physiologic data, and heterogeneity in study settings and observational study designs.
In 2010, there were more than 69,700 helicopter transports for trauma to US Level I and II trauma centers; 44,700 (64%) were from the scene of injury.31 According to the Medicare Fee Schedule, insurance companies reimburse $5,000 to $6,000 more per transport than ground ambulance, which means $200 to $240 million more was spent with this modality for trauma scene transport in 2010.32 Furthermore, a systematic review has shown than more than half of the patients flown have minor or non–life-threatening injuries that would likely have similar outcomes if transport were by ground.33 Helicopter transport also may present a safety risk. In 2008, medical helicopter crashes caused 29 fatalities, the highest number to date, provoking federal review of the safety of air medical transport.34 Currently, there is little empirical guidance on whether the routine use of helicopter EMS for trauma scene transport represents a good investment of critical care resources.
Given the limitations of the helicopter EMS outcomes literature, we aimed to determine the minimum reduction in mortality or long-term disability provided by helicopter EMS for its routine use to be considered cost-effective over ground EMS for the transport of patients from the scene of injury to a trauma center. We assessed these clinical thresholds relative to current evidence about effectiveness of helicopter transport. In this study, we account for transport costs and safety, as well as the inevitable overtriage of patients with minor injuries to helicopter transport.
Section snippets
Study Design
We developed a decision-analytic Markov model to compare the costs and outcomes of helicopter versus ground EMS trauma transport to a trauma center from a societal perspective during a patient lifetime. Clinical data and cost inputs were derived from the National Study on the Costs and Outcomes of Trauma (NSCOT),4, 35 supplemented by the National Trauma Data Bank,31 Medicare reimbursements,32 and the literature. We applied the model to a nationally representative population of trauma victims
Results
Using the base case assumptions, helicopter EMS needs to provide a 15% reduction in mortality (RR 0.85) for patients with serious injuries (Abbreviated Injury Score 3 to 6) to be below the threshold of $100,000 per quality-adjusted life-year gained (Figure 2A). Given the baseline inhospital mortality of 7.6% for the base case, a 15% RR reduction equates to a 1.3% reduction in absolute mortality. Thus, helicopter EMS would have to save a minimum of 1.3 lives per 100 patient transports with mean
Limitations
Given that there have been no previous studies comparing the long-term costs and outcomes by EMS transport mode, this analysis has a number of limitations. The decision model required certain assumptions and used data from national data sets and numerous published studies. The results and conclusions are therefore specific to those assumptions and data. For example, baseline mortality probabilities and hospitalization costs inputs were derived from NSCOT, in which most trauma centers were
Discussion
Compared with ground EMS transport, helicopter scene transport is cost-effective if it results in a reduction in the RR of death for seriously injured trauma patients of at least 15%, given our model assumptions. This translates into the need to save at least 1.3 lives per 100 patients transported with serious injury. Given current uncertainties, helicopter EMS must reduce mortality by more than 26% (2.7 lives per 100 transports with serious injury) to have a 95% probability of being
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Please see page 352 for the Editor's Capsule Summary of this article.
Supervising editor: Robert A. De Lorenzo, MD, MSM
Publication date: Available online April 9, 2013.
Author contributions: MKD and JDG were responsible for study conception and design. MKD and SW were responsible for acquisition of data. MKD, SW, and JDG-F were responsible for statistical analysis. MKD, KLS, NEW, DAS, SW, DKO, and JDG-F were responsible for analysis and interpretation of data. MKD was responsible for drafting the article. KLS, NEW, DAS, SW, DKO, and JDG-F were responsible for critical revision of article for important intellectual content. MKD takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Dr. Delgado was supported by the Agency for Healthcare Research and Quality (AHRQ) training grant to Stanford University (T32HS00028). Dr. Wang was supported by the National Institutes of Health (NIH)/National Institute of Child Health & Human Development (NICHD) (K23HD051595-02). Dr. Goldhaber-Fiebert was supported in part by an NIH/National Institute on Aging (NIA) Career Development Award (K01AG037593-01A1). Dr. Owens is supported by the Department of Veterans Affairs. This work is the sole responsibility of the authors and does not necessarily represent the official views of the AHRQ or NIH or the Department of Veterans Affairs; these agencies were not involved in the design and conduct of the study; collection, management, and interpretation of data; or the preparation, review, or approval of this article.
Corrected online September 3, 2013. See Supplemental Material online at www.annemergmed.com for an explanation of the corrections.