Impact of Pharmacist-Led Polypharmacy Management on Prescribing Patterns in Older Inpatients: A Real-World Study in a Chronic Care Hospital

Polypharmacy is a major challenge in geriatric pharmacotherapy and is associated with increased risks of adverse drug events, functional decline, and increased healthcare costs. Although pharmacist-led medication reviews improve prescription appropriateness, evidence regarding the sustained implementation of such interventions in chronic care hospitals remains limited. This study aimed to evaluate the impact of a stepwise pharmacist-led polypharmacy management program on prescription patterns and medication costs among older inpatients in a chronic care hospital. We conducted a single-center, retrospective observational study at a chronic care hospital in Japan, and included all inpatients hospitalized between January 2023 and December 2025. A multidisciplinary polypharmacy management program was introduced in 2024, followed by pharmacist-led comprehensive medication evaluation and management in 2025. The study period was categorized into three phases: preintervention (2023), implementation (2024), and comprehensive management (2025). The primary outcome was the monthly average number of regularly prescribed oral medications. The secondary outcomes included the prevalence of polypharmacy, defined as the concurrent use of ≥ 6 regularly prescribed medications, and hyperpolypharmacy, defined as ≥ 10 medications. The threshold of ≥ 6 medications was adopted because it is used as the criterion for polypharmacy management in the Japanese national healthcare reimbursement system. The threshold of ≥ 10 medications corresponds to our hospital’s institutional criterion for identifying patients eligible for pharmacist-led comprehensive medication review. Approximately 320 inpatients were included monthly during the study period. The average number of prescribed medications decreased from 6.44 ± 3.37 in 2023 to 6.23 ± 3.52 in 2024 and 6.05 ± 3.47 in 2025. Regarding the rate of polypharmacy, the proportion of patients taking ≥ 6 or ≥ 10 medications decreased from 54.3% to 46.5% and from 18.4% to 15.5%, respectively. In contrast, the total annual medication costs showed no significant changes across the 3 years. Analysis according to therapeutic class demonstrated decreased costs for hypnotics/anxiolytics and nonsteroidal antiinflammatory drugs/paracetamol, whereas antithrombotic drug costs increased. The prescription volume measured by defined daily dose per 100 patients per day (DPD) remained generally stable, although intergroup differences were observed in 2025. Pharmacist-led polypharmacy management was associated with changes in prescribing patterns and reductions in medication burden in this chronic care hospital. However, the reductions in the number of medications did not translate into short-term reductions in medication costs. These findings suggest that pharmacist-led interventions in chronic care settings may contribute to reducing medication burden and modifying prescribing patterns beyond simple medication count reduction. These findings also highlight the importance of using multiple indicators when evaluating deprescribing strategies.