Excessive polypharmacy and potentially inappropriate prescribing in 147 care homes: a cross-sectional study

BACKGROUND: Care home residents often have multiple cognitive and physical impairments, and are at high risk of adverse drug events (ADEs). AIM: To describe excessive polypharmacy and potentially inappropriate prescribing predisposing care home residents to ADEs. DESIGN & SETTING: A cross-sectional analysis of all dispensed prescriptions for 147 care home residents in Tayside and Fife, Scotland. METHOD: Prevalence of excessive polypharmacy was examined using multilevel logistic regression, by modelling associations between individual and care home predictors with excessive polypharmacy (≥10 drugs). Prescribing of drugs known to increase the risk of eight clinically important ADE categories was examined. Drugs prescribed within each ADE category, for each resident, were counted. RESULTS: In total, 32.3% (n = 1444/4468) of residents had excessive polypharmacy, which was more common in residents aged 70–74 years (adjusted odds ratio [aOR] 1.86, 95% confidence interval [CI] = 1.04 to 3.34) and 80–84 years (aOR 1.75, 95% CI = 1.01 to 3.02), living in a residential care home (aOR 1.50, 95% CI = 1.19 to 1.88), and located in Fife (aOR 1.37, 95% CI = 1.09 to 1.71). Excessive polypharmacy was less common in residents with dementia (aOR 0.73, 95% CI = 0.64 to 0.84), and 8.9% (95% CI = 5.9% to 11.6%) of the variation was attributable to care home predictors. Potentially inappropriate prescribing of ≥2 drugs was seen across all ADE categories, with highest prevalence seen in drugs predisposing to constipation (35.8%), sedation (27.7%), and renal injury (18.0%). CONCLUSION: Excessive polypharmacy is common in care home residents and is associated with both individual and care home predictors. Potentially inappropriate prescribing of drugs that predisposed residents to all included ADE categories is common. Research is needed to support and evaluate safe care home prescribing practices.