Trends in dental visits during the state of emergency for COVID-19 in Japan: a retrospective observational study

Objectives To determine national medium-term trends in dental visits during three COVID-19 emergency declaration periods in Japan and to analyse how these trends varied according to prefectural emergency measures and COVID-19 incidence. Design and setting A retrospective observational study of Japan's dental claims from January 2017 to December 2021. Data sources Data from a monthly report by the Health Insurance Claims Review and Reimbursement Services (HICRRS) in Japan. HICRRS handles the claims of employer-based health insurance. Data analysis We determined the number of monthly dental claims nationwide from January 2017 to December 2021 and the percentage change in the number of monthly dental claims based on the difference in the COVID-19 alert level between the three emergency declaration periods in 2020-2021 and the corresponding periods in 2019. Results were analysed using descriptive statistics, multiple regression model, graphical figures, and narrative synthesis. Outcome measures The main outcome was the change in the number of dental visits between the emergency declaration periods in 2020-2021 and the corresponding periods in 2019. We also assessed the difference in the number of dental visits based on the COVID-19 alert level. Results The data set included a total of 736 946 088 dental claims. Until the end of 2021, the greatest decrease in monthly dental claims was in April 2020, which was 22.3% lower than that in April 2019. As indicated by the coefficient in the regression model, the percentage change in monthly dental claims decreased by 5.01% (95% CI -8.27 to -1.74) depending on the difference between the prefectures designated as being under special precautions and other prefectures. Conclusions The decrease in dental visits was greater during the first state of emergency, ie, April-May 2020, and in prefectures designated as being under special precautions. Further efforts to promote appropriate dental visits at different alert levels are necessary.