Validation of the LGBT-DOCSS-JP among medical students: psychometric properties of a modified 16-item version

Abstract Background Medical education is critical for addressing health disparities among sexual and gender minority (SGM) populations. The Japanese version of the Lesbian, Gay, Bisexual, and Transgender Development of Clinical Skills Scale (LGBT-DOCSS-JP) is an 18-item self-assessment tool measuring clinical skills for providing healthcare to SGM patients. Although validated among healthcare professionals, its psychometric properties remain unverified in undergraduate medical students. This study therefore evaluated the reliability and validity of the LGBT-DOCSS-JP in this specific population. Methods A cross-sectional online survey was conducted at three medical universities in Japan. Structural validity was assessed using confirmatory factor analysis (CFA). Known-groups validity was evaluated by comparing scores based on SGM status, gender, and awareness of SGM individuals within personal networks. Internal consistency was measured using Cronbach’s alpha and ordinal McDonald’s omega. Results Of the 751 respondents, 735 valid responses were analyzed. The initial CFA did not support the previously established 18-item four-factor structure. Due to extreme floor effects and severe non-normality, items 13 and 16 were removed as conceptually unsuitable for students lacking clinical experience. The modified 16-item model achieved acceptable fit (RMSEA = 0.067, CFI = 0.93, TLI = 0.92, SRMR = 0.054). Regarding known-groups validity, SGM individuals scored significantly higher than cisgender heterosexual participants on all domains except Clinical Training. Cisgender heterosexual women demonstrated higher total, Attitudinal Awareness, and Basic Knowledge scores than cisgender heterosexual men. Furthermore, greater awareness of SGM individuals within personal networks was associated with higher overall scores. Cronbach’s alpha and ordinal omega demonstrated acceptable to excellent internal consistency for the total scale and its subscales. Conclusions The modified 16-item version of the LGBT-DOCSS-JP demonstrated acceptable structural validity, known-groups validity, and internal consistency among Japanese medical students. This scale provides a standardized, evidence-based tool for the self-assessment of medical students, supporting the development of targeted SGM health curricula.