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Mapping the internationally reported evidence on physician-staffed helicopter transport in Japan: a scoping review
Shunichiro Nakao1, Yoshinori Yokono2, Junya Shimazaki3
1Department of Traumatology and Acute Critical Medicine, The University of Osaka, Suita, Japan shunichironakao@hp-emerg.med.osaka-u.ac.jp.
Objectives:
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.
Design:
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).
Data Sources:
MEDLINE, Web of Science, CINAHL and the Cochrane Library, supplemented by backward and forward citation tracking.
Eligibility Criteria:
Original studies evaluating physician-staffed HEMS in Japan and reporting patient outcomes for any emergency condition published in English-language journals.
Methods:
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.
Results:
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.
Conclusion:
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.