Research note changes in the number of outpatient visits in Japan during the COVID-19 pandemic

OBJECTIVE: This study aimed to determine the change in the number of outpatient visits in Japan since the beginning of the COVID-19 pandemic, using data on the outpatient claims submitted by medical institutions to insurers in 2019 and 2020, from the National Database of Health Insurance Claims and Specific Health Check-ups. We calculated the total number of outpatient visits, and number of visits for individual diseases according to the International Classification of Diseases-10 codes on the claim form. RESULTS: The number of outpatient visits per million people decreased by 9.98% in 2020 compared to 2019. Of the diseases included in the analysis, 71 showed a decrease in the number of visits by ≥ 1%. There were significant decreases in the number of visits related to infectious diseases (influenza, acute bronchitis, and acute laryngitis, etc.), and chronic diseases (hemorrhoids, cystic kidney disease, dyspepsia, and chronic sinusitis, etc.). The observed decreased rate of outpatient visit might have been due to, a decrease in the incidence of disease, a decreased frequency of visit by patients with the disease, or both. Our analysis method using actual health insurance claim data can be applied worldwide, where researchers have access to national information on health insurance claims.