We aimed (1) to review the trends in medical care plans for mental illness and their clinical indicators, and (2) to investigate trends in psychiatric service use in fiscal year 2013 through 2019 in Japan using a nationwide claims database (NDB). Results from the NDB suggest that: (1) because medical care needs for comorbid physical illness in psychiatric inpatients increase with aging, medical care for physical illness in inpatient psychiatric care and their evaluation are important; (2) because the management of dementia in general inpatient care has been provided largely by nursing staff and most medical institutions do not have consultation-liaison psychiatry services, there may be a room for care by psychiatrists; and (3) there is a marked increase in the number of outpatients in psychiatric health services; thus, attention should be given to this trend.
 Author's abstract