Cross-Sectional Study on Factors Associated with Hyperpolypharmacy and Medication Adherence in Older Adults with Multimorbidity and Polypharmacy

Background: Knowledge of multiple medication use and medication adherence is important to assess treatment effectiveness and prevent worsening of disease, re-hospitalization, and increased healthcare costs. Limited data exist on individuals with hyperpolypharmacy (ten or more concurrent medications) and their adherence. Objective: The objective of the study was to identify potential factors associated with hyperpolypharmacy, and medication adherence in participants with hyperpolypharmacy, as well as explore the relationship between hyperpolypharmacy and medication adherence. Methods: This is a cross-sectional analysis of baseline data from OPERAM, a multicenter study across four large European hospitals. Adults aged ≥ 70 years with multimorbidity and polypharmacy (five or more regular medications) were included. Demographic, clinical, and healthcare utilization data were assessed. Outcomes were hyperpolypharmacy and low/medium medication adherence (i.e., a score < 8 out of a maximum of 8) based on the Morisky Medication Adherence Scale-8 (MMAS-8^©). Multivariable logistic regression was used to identify factors associated with hyperpolypharmacy or low/medium adherence. Results: Of 2005 patients with multimorbidity and polypharmacy, 1029 (51%) exhibited hyperpolypharmacy. In multivariable analyses, the following factors were significantly associated with hyperpolypharmacy: increasing number of comorbidities (p for linear trend < 0.001), nursing home residency (odds ratio [OR] 2.20, 95% confidence interval [CI] 1.42–3.41), and visits to specialists/emergency department (OR 1.60, 95% CI 1.16–2.19) or any hospitalizations (OR 1.89, 95% CI 1.42–2.52) compared with visits to primary care physicians only. In the subgroup of 978 hyperpolypharmacy-only adults with available adherence data, 517 (53%) had low/medium medication adherence. In multivariable analyses, the odds of low/medium medication adherence increased with increasing number of comorbidities (p for linear trend 0.005) but decreased with older age (OR 0.69, 95% CI 0.52–0.92 for ≥ 80 versus < 80 years) and receipt of community nurse care (OR 0.59, 95% CI 0.44–0.81). Conclusions: More than half of older adults with hyperpolypharmacy had suboptimal medication adherence. Our findings suggest that primary care physicians may contribute to reducing hyperpolypharmacy, while introduction of community nurse visits could improve medication adherence.