Analysis of risk factors for polypharmacy and excessive polypharmacy.

BACKGROUND: Polypharmacy is a growing global concern, particularly among older adults with multimorbidity. Fragmented care and consultations across multiple medical institutions may further increase medication burden. This study aimed to identify risk factors for polypharmacy and excessive polypharmacy in an outpatient population. METHODS: This single-center retrospective observational study included 326 outpatients aged ≥ 65 years at Tohoku Medical and Pharmaceutical University Hospital. Polypharmacy and excessive polypharmacy were defined as the use of ≥5 and ≥10 medications, respectively. The association between age and number of medications was evaluated using Spearman's rank correlation. Differences in the number of medical institutions consulted were assessed with the Wilcoxon rank sum test. Independent risk factors were identified using multiple logistic regression analysis. RESULTS: The mean age was 74.0 ± 18.3 years. Age showed a significant positive correlation with the number of medications (r = 0.39, p < 0.001). Patients with polypharmacy or excessive polypharmacy consulted significantly more medical institutions than those without (p = 0.0004 and p = 0.0011, respectively). Multivariate analysis demonstrated that age, hypertension, gastrointestinal disorders, diabetes, neuropsychiatric disorders and number of medical institutions consulted were independent risk factors for both polypharmacy and excessive polypharmacy. CONCLUSION: Aging and chronic disorders were substantially associated with polypharmacy. Although consultation with multiple medical institutions was statistically associated with increased medication burden, the observed effect size was modest, suggesting that fragmented care may contribute only incrementally to polypharmacy in this population. Integrated care strategies and medication review processes may nevertheless help reduce inappropriate polypharmacy and enhance patient safety.