The purpose of this study was to review the changes occurring in psychiatric inpatient care in Japan based on long-term data from a nationwide survey of mental health and welfare (630survey) and future estimates of the number of hospitalized patients.
 Based on the 630survey, we examined the number of inpatients nationwide by length of stay, age group, and diagnosis. We also examined the proportion of newly admitted patients by age group and diagnosis in June 2004, 2010, and 2015. In addition, we examined the changes occurring in psychiatric inpatient care by adding the number of F0 and F2 inpatients by prefecture based on the findings of the 630survey, and the estimated future number of patients based on patient surveys, 630survey, and the Database of Receipt Information and Specific Health Examination Information.
 There was almost no change in the number of patients in the "less than 1 year" category by length of hospital stay, whereas there was a gradual decrease in the "1 to 5 years" category and a large decrease in the "5 years or more" category. By age group, the number of patients in the "20 to 40" and "40 to 65" categories decreased significantly, whereas the number of patients in the "75 and older" category increased. The proportion of new inpatients "75 and older" also increased. These changes can be attributed to the changing mental healthcare needs of the region against the backdrop of a declining and aging population, advances in psychiatric care, and changes in public awareness. These findings suggest the content of psychiatric care needed in urban areas and the availability of psychiatric care in rural areas.
 The decrease in the number of inpatients in psychiatric beds may have a significant impact on the state of inpatient psychiatric care and the community mental health care in the region. It is necessary to work on securing mental health care that is suited to each region.
 Authors' abstract