Transdiagnostic Assessment of Mental Health and Sleep Registry: Protocol for a Cross-Sectional Study.

Background: Mental disorders impose a substantial burden on individuals and society that cannot be fully captured by diagnostic labels or clinial indicators alone. Accordingly, the need for approaches that comprehensively assess patients' subjective experiences and daily functioning is growing. Patient-reported outcomes (PROs) enable multidimensional assessment from the patient's perspective and are increasingly important in mental health research. However, prior studies have frequently assessed these domains in isolation using different instruments and assessment schedules, limiting individual-level integration and cross-study comparability. The focus on single diagnostic groups has further impeded transdiagnostic understanding, and the lack of harmonized data standards has restricted data sharing and reuse. This study protocol describes the establishment of the Transdiagnostic Assessment of Mental Health and Sleep (TAMS) registry, a multidimensional PROs registry designed to enable transdiagnostic comparisons across individuals with mental disorders and physical conditions, as well as healthy participants. Methods and Analysis: We will conduct a nationwide registry-based cross-sectional study in Japan. Participants will include adults with mental disorders, those with physical conditions, and healthy participants, recruited through an online survey company. After providing electronic consent, all participants will complete an online survey providing information on demographics, diagnoses, and treatment. The registry will also capture information on Quality of Life (QOL) as well as related psychosocial factors, psychiatric symptoms, sleep characteristics, and attitudes toward digital health technology. Data collection is planned for March 2026, with a target enrollment of 3300 participants. Planned analyses will validate patient-reported instruments and characterize how these variables are related to QOL. Ethics and Dissemination: This study has received ethical approval (ID R07-137) and will be conducted in accordance with national information security guidelines, with voluntary participation, digital informed consent, and findings will be disseminated through peer-reviewed publications and plain-language summaries. The registry will be released as a publicly accessible dataset in accordance with the data-sharing guidelines of the FAIR principles (Findable, Accessible, Interoperable, and Reusable). Clinical Trial Registration: The study has been registered on https://jrct.mhlw.go.jp/ (registration number: jRCT1030250737; registration link: https://jrct.mhlw.go.jp/latest-detail/jRCT1030250737).