Mapping the internationally reported evidence on physician-staffed helicopter transport in Japan: a scoping review.

Abstract

Japan's physician-staffed helicopter emergency medical services (HEMS) are widely deployed but published evidence is heterogeneous across indications, outcomes and study designs. We aimed to map the internationally reported, English-language literature evaluating physician-staffed HEMS in Japan and to identify evidence gaps requiring further research. Scoping review was conducted using established methodological frameworks and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). MEDLINE, Web of Science, CINAHL and the Cochrane Library, supplemented by backward and forward citation tracking. Original studies evaluating physician-staffed HEMS in Japan and reporting patient outcomes for any emergency condition published in English-language journals. We conducted a systematic database search using terms related to physician-staffed HEMS in Japan. The original search (28 May 2024) was updated on 25 February 2026 using the same eligibility criteria. Two reviewers independently performed title/abstract screening followed by full-text screening to determine eligibility. We additionally performed backward and forward citation tracking of the included studies. We summarised characteristics of eligible studies descriptively using counts and proportions. The updated search identified 341 records, and citation tracking identified 16 further studies, yielding 76 included studies. Publications increased over time (2016-2020: 32.9%; 2021-2026: 52.6%). Most studies were single-centre observational (55.3%) or registry-based (39.5%), with few multi-centre studies (5.3%). Trauma was the most frequent study population (25.0%), and mortality the most common primary outcome (35.5%). First authors were university-affiliated in 88.2% of studies, 39.5% appeared in a single aeromedical journal, and no study compared physician-staffed with non-physician HEMS. The internationally reported, English-language literature on physician-staffed HEMS in Japan has expanded over time, but remains dominated by retrospective observational designs, is produced largely by university-affiliated authors, and is concentrated in a small number of journals. Prospective multi-centre evaluation, comparison with non-physician HEMS, functional and longer-term outcomes, and economic evaluation were absent from the identified literature.