(B-147) Impact analysis of the recent policy interventions for regional polypharmacy reduction in Japan with high older population: A nationwide serial cross-sectional study (April 2020-March 2023)

Background: Polypharmacy is a global health issue for older adults, and Japan is not an exception due to rapidly aging society. Recently, operational instructions to initiate a polypharmacy management system for older adults in each hospital was published in March 2021, and bi-annual medical fee amendments by Ministry of Health, Labor and Welfare (MHLW), including incentives to reduce polypharmacy were implemented in April 2022.

Objectives: This study analyzed the impact of new polypharmacy reduction policies in Japan during the COVID-19 pandemic. The hypothesis is that these policies effectively reduced nationwide polypharmacy.

Methods: This study is a serial cross-sectional study based on annual prescription-based reimbursement claim data (FY2020: April 2020-March 2021, FY2021: April 2021-March 2022, FY2022: April 2022-March 2023) from national database (NDB). Older adults were defined as 75 years and above in this study following a new academic definition in Japan. The primary outcome was the polypharmacy proportion (PP) defined as percentage of annual prescriptions with 7 medications or more out of total annual prescription. The data of 335 secondary medical areas (SMAs) were set as samples in this study, and MHLW designated SMAs as a regional unit of advanced medical access. Paired t-test was conducted for the means of polypharmacy proportion based on SMAs, p value (two-sided) < 0.05 was considered statistically significant. Stratification analysis was conducted based on sex and 75 years or above.

Results: The means (95% CI) of PP based on total SMAs (n=335) was 4.16% (4.04-4.27) for FY2020, 4.04% (3.93-4.15) for FY2021, and 3.86% (3.76-3.97) for FY2022. Statistically significant reduction was observed respectively among each fiscal year with p values less than 0.001 by paired t-test, and the mean (95%CI) of reduction ratio for PP from FY2020 to FY2022 based on total SMAs (n=335) was 6.96% (6.45-7.47).
Additionally, the stratifications by sex or age exhibits that entire nationwide PP was reduced from FY2020 (male: 4.14%, female: 3.31%, 75 years or above: 6.41%) to FY2022 (male: 3.90%, female: 2.96%, 75 years or above: 6.04), and the reduction ratio of PP from FY2020 to FY2022 are 5.79% (male), 10.83%(female), and 5.77%(75 years or above), respectively.

Conclusions: A significant reduction in nationwide polypharmacy was observed after new policies were implemented during the COVID-19 pandemic in Japan. However, the more effective policies are needed for older population since the mean of PP (75 years or above) remains high in FY2022.