Nationwide changes in legal status after mandatory renewal of medical-protection hospitalization in Japan.

BACKGROUND: In April 2024, Japan introduced mandatory periodic renewal of Involuntary Hospitalization for Medical Care and Protection (medical-protection hospitalization), a form of involuntary psychiatric hospitalization used when inpatient treatment is required but voluntary admission is not possible. We examined nationwide changes after implementation of this reform. METHODS: We analyzed aggregate data from the nationwide 630 Survey, the Report on Public Health Administration and Services, and the Hospital Report. The primary comparison was between June 2024 and June 2025, with particular attention to the first statutory renewal point at three months. Historical patterns, one-year outcomes, and patient characteristics were also examined. RESULTS: Medical-protection inpatients decreased from 121,468 to 105,264 (-13.3%), whereas voluntary inpatients increased from 126,326 to 139,799 (+10.7%); their combined number decreased by only 1.1%. The medical-protection proportion changed little among patients hospitalized for <3 months (50.54% to 49.92%) but decreased markedly among those hospitalized for ≥ 3 months (48.58% to 40.89%; interaction OR 0.751, 95% CI 0.731-0.771). No comparable three-month pattern was observed in the preceding eight annual surveys. Among episodes remaining hospitalized at one year, the voluntary proportion increased from 11.92% to 26.15% (OR 2.62, 95% CI 2.35-2.92). CONCLUSIONS: The first-year decline in medical-protection hospitalization primarily reflected a redistribution of legal admission status among continuing inpatients rather than a comparable reduction in psychiatric hospitalization itself. Longer follow-up is needed to determine its effects on autonomy, discharge, and long-term hospitalization.