Impact of the antimicrobial stewardship incentive program on antimicrobial supply instability: An interrupted...

In April 2024, Japan introduced an antimicrobial stewardship incentive program to promote the use of Access antibiotics on the basis of the World Health Organization Access, Watch, Reserve (AWaRe) classification. However, concerns have arisen about how the increased demand for Access antibiotics could exacerbate supply instability, given that antimicrobial shortages have been reported around the world since the late 2010s. In this study, we evaluated the impact of this incentive program on antimicrobial supply stability by using national supply monitoring data.

We conducted a retrospective observational study by using publicly available monthly antimicrobial supply data from Japanese pharmaceutical manufacturers. The primary outcome was the monthly normal supply rate of antimicrobial products, and the secondary outcomes included supply status stratified by AWaRe category and formulation. Interrupted time-series analysis using binomial models adjusted for autocorrelation was performed to assess immediate and longitudinal changes before and after program implementation. Three sensitivity analyses were conducted: one adjusting for seasonality, one restricted to products with complete 24-month data, and one utilizing non-antimicrobial products as controls.

A total of 856 antimicrobial products were identified. Following the implementation of the incentive program, the proportion of products under normal supply significantly increased immediately and over time across all categories, except for Reserve antimicrobial products and Access penicillins. The sensitivity analyses yielded consistent results.

There was no association between the antimicrobial stewardship incentive program and the worsening antimicrobial supply instability. Therefore, financial incentives that promote appropriate antimicrobial use may be implemented without compromising supply stability.