The impact of the Mental Health Act revision for deinstitutionalization in Korea on the crime rate of people with schizophrenia

•The Mental Health Act in Korea was revised in 2017 in order to return hospitalized psychiatric patients to the community.•The rates of total crime and violence among patients with schizophrenia increased after the law revision.•The revision did not lead to an increase in the murder rate of people with schizophrenia as is commonly thought.•The increases in overall crime and violence rates suggest that the deinstitutionalization may not have led to a successful relocation of patients into the community. This study examined changes in the crime rates of people with schizophrenia in Korea in comparison with the general population after the Mental Health Act revision for deinstitutionalization in 2017. The crime rates of people with schizophrenia and the general population were calculated from 2012 to 2021 using the Korean National Police Agency crime statistics. The effects of the law revision in 2017 on the crime rates were assessed using the interrupted time series and difference-in-difference analyses. The crime rates of people with schizophrenia tended to be lower than the general population except for murder and arson, which were 5.3 and 11.4 times, respectively, that of the general population. While no significant effect of the revision was found in the interrupted times series analysis, the difference-in-differences analysis indicated that the total crime rates and the rates of violence and public order crime increased among people with schizophrenia compared with the general population. The revision of the Mental Health Act for deinstitutionalization did not lead to an increase in the murder rate of people with schizophrenia as is commonly thought. However, the increases in overall crime and violence rates of people with schizophrenia suggest that the deinstitutionalized patients may not have been successfully relocated into the community. The increase in crime after the revision should be interpreted as a call for well-resourced community care rather than the reason for re-transfer of patients to hospitals.