Visualizing regional variations in psychiatric inpatient outcomes for schizophrenia and mood disorders: a nationwide administrative database study in Japan

Optimizing psychiatric outcomes, such as reducing coercive measures and chlorpromazine dosage, is crucial for ensuring patient autonomy and deinstitutionalization amid the increasing prevalence of mental disorders. Ensuring equitable psychiatric care regardless of location is a pressing healthcare priority. International evidence suggests regional disparities in care quality; however, nationwide database studies in Japan remain limited. We aimed to clarify regional differences in clinical outcomes, including mortality, seclusion and restraint use, and chlorpromazine dosage reduction, among inpatients with schizophrenia and mood disorders in Japan. This retrospective observational study used data from Japan’s nationwide Diagnosis Procedure Combination database (fiscal years 2016–2022) of acute-care hospitals with psychiatric departments. Inpatients with schizophrenia or mood disorders were included. Outcomes included in-hospital mortality, seclusion, physical restraint, and chlorpromazine-equivalent dose (CPZE) reduction. Regional disparities were evaluated using urban–rural classifications and seven regional blocks. Multivariate logistic and Fine–Gray proportional hazards regression analyses were performed, adjusting for patient and hospital factors. Among 38,124 patients, significant regional disparities were observed in physical restraint and chlorpromazine dosage reduction but not in mortality. For schizophrenia, depopulated areas had lower odds of restraint use ( p < 0.01). For mood disorders, CPZE reduction was significantly less likely in Regional core city and depopulated areas ( p < 0.01). Although urban–rural classification showed no difference in seclusion, regional block analysis revealed marked variations. Significant regional disparities exist in psychiatric inpatient outcomes in Japan, particularly regarding physical restraint and medication adjustment. These findings highlight the need for standardized care and policies to ensure equitable outcomes across regions.