Polypharmacy is a determinant of hospitalization in Parkinson's disease.

Patients with Parkinson's disease (PD) are at a higher risk of hospitalization and recurrent hospitalizations, with consequent complications. Polypharmacy is associated with several adverse outcomes, including hospitalization, increased length of hospital stay, and mortality. The aim of this study was to evaluate among patients with PD the association between the number of medications and incident hospitalizations. We analysed the data of 165 patients with Parkinson's disease attending a geriatric Day Hospital who were enrolled in a cohort study and followed for a median of two years. Over the follow-up, 46 participants (46%) were hospitalized at least one time; multiple admissions were observed in 12 subjects (7%). The median number of agents was 5 (4-7). In Cox regression, the number of drugs was associated with increased hospitalization rates (HR=1.23; 95% CI=1.06-1.43), also after excluding non-neurological medications (HR=1.18; 95% CI=1.01-1.38). Using Poisson regression, polypharmacy (i.e., use of >5 drugs) predicted the number of repeated hospitalizations (IRR=2.62; 95% CI=1.28-5.36; p=.008). Among patients with PD, the number of daily medications is associated with increased risk of hospitalization; an increasing number of drugs is associated with increasing number of hospitalizations.