Impact of antimicrobial resistance measures and the emergence of COVID-19 on antimicrobial use throughout the Japanese population: A retrospective cohort study using a national claims database

Objective: This study examined the impact of Japan's National Action Plan on Antimicrobial Resistance (NAP) and the COVID-19 pandemic on national trends in antimicrobial consumption (AMC) for major infectious diseases. Methods: This retrospective cohort study analyzed claims data for the Japanese population from 2013 to 2020. AMC was expressed as defined daily doses per 1,000 inhabitants per day. The target diseases included upper respiratory infection (URI), otitis media, pneumonia, diarrhea, urinary tract infection, skin and soft tissue infection, and sexually transmitted infection. Seasonally adjusted interrupted time-series analyses were conducted to assess the impact of NAP publication in 2016 and the COVID-19 outbreak in 2020 on the numbers of medically attended cases and antimicrobial prescription rates. Results: Total AMC declined from 2016 to 2019, and decreased further in 2020. There was a significant decrease in medically attended cases in 2020 when compared to the counterfactual scenario in which COVID-19 did not occur. AMC was positively correlated with the number of medically attended cases. Total antimicrobial prescription rates decreased after NAP publication and the COVID-19 outbreak. Among the diseases, prescription rates for URI, otitis media, and pneumonia significantly decreased after both events. However, the prescription rate for diarrhea decreased after NAP publication but increased after COVID-19. No significant trends were detected for other diseases. Conclusions: Antimicrobial prescriptions for respiratory infections steadily decreased after NAP publication, which may indicate the effects of antimicrobial stewardship activities. Continued monitoring is needed to clarify the long-term effects of the COVID-19 pandemic on antimicrobial use.