Comparing the Air Medical Prehospital Triage Score With Current Practice for Triage of Injured Patients to Helicopter Emergency Medical Services: A Cost-effectiveness Analysis

Abstract

Importance: Little evidence exists to guide helicopter emergency medical services (HEMS) triage, and current practice is inefficient. The Air Medical Prehospital Triage (AMPT) score was developed to identify patients most likely to benefit from HEMS compared with ground EMS. To our knowledge, no studies have evaluated the potential effect on costs and outcomes of a more targeted HEMS triage strategy, such as the AMPT score.

Objective: To evaluate the cost-effectiveness of current practice compared with the AMPT score for HEMS scene triage of trauma patients.

Design, Setting, and Participants: A cost-effectiveness Markov model was developed for the US health care system to compare current practice with the AMPT score as HEMS scene triage strategies from the health care system perspective over a patient lifetime horizon. A base case was estimated using national data of patient characteristics from the National Trauma Databank from 2007 to 2012. Model inputs, including demographic information, health care costs, survival, and utility estimates, were derived from literature and national registries. Triage strategies were modeled as probability of HEMS transport. Multilevel logistic regression was used to evaluate survival probability between HEMS and ground EMS under the triage strategies. Costs considered included transport reimbursements, hospitalization, cost of health care in the first year postinjury, and annual cost of health care after the first year postinjury. Several sensitivity analyses were performed to evaluate robustness of model assumptions.

Main Outcomes and Measures: Incremental cost-effectiveness ratio, with a threshold of $100 000 or less per quality-adjusted life-year defining cost-effectiveness.

Results: The base case had an incremental cost-effectiveness ratio of $255 333 per quality-adjusted life-year for current practice compared with the AMPT score. Assuming 20% of patients have severe injuries and assuming HEMS only benefits these patients, current practice had an incremental cost-effectiveness ratio of $176 686 per quality-adjusted life-year. Probabilistic sensitivity analysis demonstrated that current practice is inferior in 85% of iterations, only becoming favored when the cost-effectiveness threshold is greater than $310 000 per quality-adjusted life-year.

Conclusions and Relevance: Current practice is not cost-effective compared with the AMPT score for HEMS scene triage. The AMPT score was the preferred strategy across a range of model input values in sensitivity analyses. The AMPT score identifies patients most likely to benefit from HEMS while potentially reducing costs to the health care system and should be considered in air medical transport protocols for trauma patients.

Figure 1.. Decision Analytic Tree With Markov Model

A, Decision analytic tree comparing current practice with the Air Medical Prehospital Triage (AMPT) score as scene transport strategies for allocating patients to either helicopter emergency medical services (HEMS) or ground emergency medical services (GEMS). B, Markov model.

Figure 2.. Cost-effectiveness Acceptability Curve

Cost-effectiveness acceptability curve across a range of cost-effectiveness thresholds from probabilistic sensitivity analysis. The Air Medical Prehospital Triage (AMPT) score is cost-effective in 85% of iterations at $100 000 per quality-adjusted life-year, while current practice only has more cost-effective iterations when the cost-effectiveness threshold is greater than $310 000 per quality-adjusted life-year. All costs were adjusted to 2015 US dollars using the Consumer Price Index.