Frailty modifies the effect of polypharmacy and multimorbidity on the risk of death among nursing home residents: Results from the SHELTER study

BACKGROUND: Frailty, disability, and polypharmacy are prevalent in nursing home (NH) residents, often co-occurring with multimorbidity. There may be a complex interplay among them in terms of outcomes such as mortality. Aims of the study were to (i) assess whether nursing home residents with polypharmacy (5–9 medications) or hyperpolypharmacy (≥10 drugs), have an increased risk of death and (ii) whether any association is modified by the co-presence of frailty or disability. METHODS: Cohort study with longitudinal mortality data including 4,023 residents from 50 European and 7 Israeli NH facilities (mean age = 83.6 years, 73.2% female) in The Services and Health for Elderly in Long Term care (SHELTER) cohort study. Participants were evaluated with the interRAI-LongTerm Care assessment tool. Frailty was evaluated with the FRAIL-NH scale. Hazard ratio (HR) of death over 12 months was assessed with stratified Cox proportional hazards models adjusted for demographics, facilities, and cognitive status. RESULTS: 1,042 (25.9%) participants were not on polypharmacy, 49.8% (n = 2,002) were on polypharmacy, and 24.3% (n = 979) on hyperpolypharmacy. Frailty and disability mostly increased risk of death in the study population (frailty: HR = 1.85, 95%CI 1.49–2.28; disability: HR = 2.10, 95%CI 1.86–2.47). Among non-frail participants, multimorbidity (HR = 1.34, 95%CI = 1.01–1.82) and hyperpolypharmacy (HR = 1.61, 95%CI = 1.09–2.40) were associated with higher risk of death. Among frail participants, no other factors were associated with mortality. Polypharmacy and multimorbidity were not associated with mortality after stratification for disability. CONCLUSIONS: Frailty and disability are the strongest predictors of death in NH residents. Multimorbidity and hyperpolypharmacy increase mortality only in people without frailty. These findings may be relevant to identify patients who could benefit from tailored deprescription.