Impact of the early phase of the COVID-19 pandemic on the use of mental health services in South Korea: a nationwide, health insurance data-based study

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has profoundly affected the utilization of mental health services. Existing evidence investigating this issue at the nationwide level is lacking, and it is uncertain whether the effects of the COVID-19 pandemic on the use of psychiatric services differs based on psychiatric diagnosis. METHODS: Data from the claims database between October 2015 and August 2020 was obtained from the Health Insurance Review and Assessment agency in South Korea. Based on the main diagnostic codes, psychiatric patients were identified and categorized into diagnostic groups (anxiety disorders, bipolar and related disorders, depressive disorders, and schizophrenia spectrum disorders). We calculated the number of psychiatric inpatients and outpatients and the medication adherence of patients for each month. We compared the actual and predicted values of outcomes during the COVID-19 pandemic and performed interrupted time-series analyses to test the statistical significance of the impact of the pandemic. RESULTS: During the COVID-19 pandemic, the number of inpatients and admissions to psychiatric hospitals decreased for bipolar and related disorders and depressive disorders. In addition, the number of patients admitted to psychiatric hospitals for schizophrenia spectrum disorders decreased. The number of psychiatric outpatients showed no significant change in all diagnostic groups. Increased medication adherence was observed for depressive, schizophrenia spectrum, and bipolar and related disorders. CONCLUSIONS: In the early phase of the COVID-19 pandemic, there was a trend of a decreasing number of psychiatric inpatients and increasing medication adherence; however, the number of psychiatric outpatients remained unaltered. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00127-022-02382-z.