Association of Polypharmacy With 1-Year Trajectories of Cognitive and Physical Function in Nursing Home Residents: Results From a Multicenter European Study

Objectives: To test the association between polypharmacy and 1-year change in physical and cognitive function among nursing home (NH) residents. Design: Longitudinal multicenter cohort study based on data from the Services and Health for Elderly in Long TERm care (SHELTER) study. Setting: NH in Europe (n = 50) and Israel (n = 7). Participants: 3234 NH older residents. Measurements: Participants were assessed through the interRAI long-term care facility instrument. Polypharmacy was defined as the concurrent use of 5 to 9 drugs and excessive polypharmacy as the use of ≥10 drugs. Cognitive function was assessed through the Cognitive Performance Scale (CPS). Functional status was evaluated through the Activities of Daily Living (ADL) Hierarchy scale. The change in CPS and ADL score, based on repeated assessments, was the outcome, and their association with polypharmacy was modeled via linear mixed models. The interaction between polypharmacy and time was reported [beta and 95% confidence intervals (95% CIs)]. Results: A total of 1630 (50%) residents presented with polypharmacy and 781 (24%) excessive polypharmacy. After adjusting for potential confounders, residents on polypharmacy (beta 0.10, 95% CI 0.01-0.20) and those on excessive polypharmacy (beta 0.13, 95% CI 0.01-0.24) had a significantly higher decline in CPS score compared to those using <5 drugs. No statistically (P >.05) significant change according to polypharmacy status was shown for ADL score. Conclusions: Polypharmacy is highly prevalent among older NH residents and, over 1 year, it is associated with worsening cognitive function but not functional decline.