Clinical and Economic Outcomes of Korea’s National Polypharmacy Management Program for Hospitalized Older Adults: 90-Day Readmission and Healthcare Costs

Polypharmacy is a significant health concern associated with adverse outcomes in older adults. To mitigate these risks, Korea’s National Health Insurance Service implemented a hospital-based, pilot polypharmacy management program. We aimed to evaluate the clinical and economic effectiveness of the polypharmacy management program in beneficiaries aged ≥ 65 years. This retrospective cohort study evaluated the polypharmacy management program implemented across 34 hospitals (2020–21). The program targeted hospitalized patients with at least one chronic condition receiving either ten or more medications or five or more medications plus an additional high-risk factor. To address the lack of randomization, an external historical control group was established by linking pilot data with the nationwide National Health Insurance Service claims database. Propensity score matching was performed on the entire cohort with subsequent analyses restricted to those aged ≥ 65 years. The primary outcome was 90-day readmission, analyzed using Cox proportional hazards regression. A cost–benefit analysis was performed from payer and societal perspectives. The final analysis included 1135 intervention and 1125 control patients. Polypharmacy management program participants showed a lower risk of readmission compared with controls (adjusted hazard ratio = 0.85; 95% confidence interval 0.75–0.96). While emergency department visits did not differ significantly, the intervention group incurred significantly lower hospitalization costs (USD$6400 vs USD$6740, P = 0.005). The program demonstrated economic viability, yielding a benefit-cost ratio of 3.8 from a payer perspective. The polypharmacy management program effectively reduced readmissions and generated substantial cost savings. These findings underscore the importance of integrating data-driven medication management into national healthcare strategies to improve patient safety and financial sustainability.