Appropriateness of outpatient antibiotic prescriptions in acute-care hospitals in Japan: a cross-sectional study from 2016-22.

Background: Antimicrobial resistance (AMR) is a major global health concern. Japan's National Action Plan on AMR, initiated in 2016, aims to reduce antimicrobial consumption. Although overall antimicrobial consumption has declined, detailed data on the clinical appropriateness of outpatient antibiotic prescriptions remain limited. We evaluated longitudinal changes in the quality and patterns of outpatient antibiotic prescribing in Japan between 2016 and 2022. Methods: This multicentre cross-sectional chart review was conducted in Aichi Prefecture and included acute-care hospitals with antimicrobial stewardship teams. Outpatient visits with antibiotic prescriptions in 2016, 2019 and 2022 were identified, and 1000 visits per year were randomly sampled. Electronic medical records were reviewed to extract patient and prescription characteristics and to assess the appropriateness of antibiotic selection based on the recorded diagnoses. Results: Among 1 177 552 outpatient visits with antibiotic prescriptions, 2987 randomly sampled visits from 34 hospitals were analysed. Treatment prescriptions decreased (from 58.8%-46.1%), whereas medical prophylaxis increased (from 16.8%-33.4%), largely driven by trimethoprim-sulfamethoxazole use. The use of third-generation cephalosporins and macrolides declined, whereas trimethoprim-sulfamethoxazole became the most frequently prescribed antibiotic by 2022. Among the evaluable treatment prescriptions ( Conclusions: The quality of outpatient antibiotic prescribing improved during the National Action Plan period; however, persistent drug class-specific gaps indicate the need for targeted antimicrobial stewardship interventions in the post-pandemic period.