Medication overload: A closer look at polypharmacy and potentially inappropriate medications among older people in Taiwan and Japan

Background: Polypharmacy and potentially inappropriate medications (PIM) are widely recognized as vital quality indicators of pharmacotherapy in older adults. As Taiwan and Japan grapple with the ongoing challenges of population aging, obtaining an accurate understanding of the prevalence of these indicators is crucial for developing effective strategies to optimize pharmacotherapy in older populations. The present study aims to comprehensively evaluate the prevalence of polypharmacy and PIMs in Taiwan and two Japanese cohorts, shedding light on the similarities and differences in prescribing practices across these populations. Methods: This study employed a cross-sectional design to investigate individuals aged & GE;65 years in Taiwan, as well as two Japanese cohorts: Japan Cohort 1 (dispensing data from chain pharmacies; year 2014 and 2019) and Japan Cohort 2 (claims data; year 2017 and 2019). The prescription records of these participants were collected from the national claims database in Taiwan for the years 2014, 2017, and 2019. To identify polypharmacy and hyper-polypharmacy, the study defined the use of 5-9 and 10+ drugs, respectively. Furthermore, the study identified PIMs based on the STOPP-J criteria. Notably, the study further explored the most frequently used PIMs (by categories) in Taiwan. Results: In the year 2019, the prevalence of polypharmacy exhibited similar rates in Taiwan (35.4%) and Japan Cohort 2 (33.1%), while surpassing that of Japan Cohort 1 (25.6%). Nonetheless, the incidence of PIMs in Taiwan was the highest (66.5%), exceeding those of the two Japanese cohorts (Cohort 1: 43.7% and Cohort 2: 40.2%) in the same year. Notably, the top three categories of commonly used PIMs in Taiwan comprised nonsteroidal anti-inflammatory drugs (NSAIDs), antithrombotic drugs, and benzodiazepines. Conclusions: This study highlights the varying prevalence of polypharmacy and PIMs between Taiwan and Japan, but emphasizes the need for collaborative efforts towards optimizing pharmacotherapy in older adults.