Association between Pre-Admission Polypharmacy and Functional Status at Discharge in Patients with Acute Stroke: A Retrospective Observational Study

Introduction: Polypharmacy is prevalent among stroke patients and has been associated with adverse outcomes in elderly individuals. However, its impact on functional recovery in the acute phase of stroke remains uncertain. The present study examined the association between polypharmacy at admission and functional outcomes at discharge in patients with acute stroke. Methods: A retrospective observational study was conducted on patients aged ≥18 years who were admitted with ischemic or hemorrhagic stroke to a Japanese university hospital between September 2022 and October 2023. Polypharmacy was defined as the use of ≥5 pre-admission regular medications confirmed at the time of admission; medications newly initiated after admission were not included. The primary outcome was the total Functional Independence Measure (FIM) score at discharge, and FIM gain during hospitalization was a secondary outcome. Patients were divided into two groups: those who were prescribed multiple medications (polypharmacy group) and those who were not (non-polypharmacy group). Multiple linear regression analysis was used to evaluate whether polypharmacy was independently associated with FIM at discharge after adjustment for age, comorbidities, pre-stroke disability, stroke severity, serum albumin, and baseline FIM scores. A sensitivity analysis was conducted in patients aged ≥65 years. Results: Of the 339 eligible patients, 303 were included in the final analysis; 170 (56.1%) had polypharmacy. Patients with polypharmacy exhibited lower total FIM scores at admission and discharge, in addition to diminished FIM gain and prolonged hospital stays when compared with patients without polypharmacy. In the fully-adjusted model, polypharmacy remained independently associated with lower total FIM at discharge (adjusted difference -5.3 points, 95% confidence interval -9.5 to -1.1; p = 0.013). Analogous associations were observed in the analysis restricted to patients aged ≥65 years. Conclusions: Pre-admission polypharmacy was associated with lower functional status at discharge, but not with FIM gain, in patients with acute stroke. These findings suggest that pre-admission polypharmacy may serve as a marker of clinical complexity and help identify patients at risk of poorer discharge functional status.