The effects of Japan’s National Action Plan on Antimicrobial Resistance on antimicrobial use

•The National Action Plan on Antimicrobial Resistance significantly reduced antimicrobial use in Japan.•The plan resulted in both an immediate and accelerated reduction in antimicrobial use.•These changes were observed for total and broad-spectrum oral antimicrobials.•Parenteral antimicrobial use did not decrease after implementation of the plan. The aim of this study was to estimate the effects of Japan’s National Action Plan on Antimicrobial Resistance 2016–2020 (NAP) on antimicrobial use (AMU). Monthly AMU from January 2013 to December 2019 was calculated using sales data, and time-series charts of AMU were then created for the total antimicrobials and target drug categories shown in the NAP (oral cephalosporins, oral fluoroquinolones, oral macrolides, and parenteral antimicrobials). Twelve-month predictions were generated to evaluate AMU in 2020. The publication of the NAP was associated with an AMU reduction in total antimicrobials, cephalosporins, fluoroquinolones, and macrolides. Parenteral AMU showed an upward trend, although it was not significantly associated with the intervention effect. AMU reductions of 15.0% for total antimicrobials, 26.3% for cephalosporins, 23.5% for fluoroquinolones, and 24.6% for macrolides were predicted for 2020 relative to 2013. However, there was a predicted increase of 17.4% for parenteral AMU. While Japan’s NAP has contributed to the reduction in national AMU over the past 5 years, sustained action is still needed to further improve antimicrobial stewardship and promote countermeasures to antimicrobial resistance.