Helicopter Emergency Medical Services Outcomes Research 1983 to 2022: Evidence Overview and Longitudinal Trends.

OBJECTIVE: Helicopter emergency medical services (HEMS) literature has been assessed in reviews focusing on various diagnoses, but there are few, if any, summaries of the entire body of HEMS outcomes evidence. Our goal was to summarize the existing research addressing patient-centered outcomes potentially accrued with HEMS. METHODS: As part of the Critical Care Transport Collaborative Outcomes Research Effort, we generated the HEMS Outcomes Assessment Research Database and executed descriptive analyses of longitudinal trends from 1983 to 2022. Both indexed and gray literature sources were incorporated in the HEMS Outcomes Assessment Research Database. Studies were reviewed by at least 2 authors to select those that addressed a patient-centered outcome. Studies addressing solely HEMS logistics were excluded. Categoric analyses were executed with the Fisher exact test, and continuous variables were evaluated for normality with normal quantile plotting and a comparison of medians and 95% confidence intervals. RESULTS: We found that HEMS outcomes study sample sizes increased steadily from 1983 to 2012, with the most recent decade demonstrating a marked increase in the rate of publication of HEMS outcomes studies. Most research (70.6%) addressed trauma patient outcomes, but recent decades have seen a significant increase in non-trauma studies. Recent decades have also been characterized by an increase in the production of HEMS outcomes research outside of North America and Europe. CONCLUSION: This study summarizes the current state of the HEMS outcome literature. We highlight increasing contributions from worldwide researchers and increasing focus on HEMS benefits in non-trauma cases, particularly time-critical cases such as cardiac or stroke diagnoses. This provides a basis for further investigations into patient-oriented benefits potentially accrued with HEMS.