Polypharmacy and potentially inappropriate medication use in older adults with cancer undergoing chemotherapy: Effect on chemotherapy-related toxicity and hospitalization during treatment

Objectives To evaluate the prevalence of polypharmacy and potentially inappropriate medication (PIM) use and the association between these and chemotherapy-related adverse events in older adults with cancer undergoing chemotherapy. Design Secondary analysis of prospectively collected data. Setting Outpatient oncology clinics in seven academic medical centers. Participants Adults aged 65 and older with cancer undergoing chemotherapy. Measurements Measures included number of daily medications (polypharmacy); PIM use based on three indices (Beers, Zhan, and Drugs to Avoid in the Elderly criteria), and use of six "high risk" medication classes for adverse drug events (anticoagulants, antiplatelet agents, opioids, insulin, oral hypoglycemics, antiarrhythmics). Using multivariate logistic regression, the relations were evaluated between these criteria and Grade 3 to 5 chemotherapy-related toxicity and between these criteria and hospitalization during chemotherapy. Results Participants (N = 500; mean age 73, 61% Stage IV disease) took a mean of 5 ± 4 daily medications (range 0-23). PIM use was common (up to 29% according to Beers criteria). No association was found between number of daily medications (reference 0-3 medications) and toxicity (4-9 medications, odds ratio (OR) = 1.34, 95% confidence interval (CI)=0.92-1.97; ≥10 medications, OR=0.82, 95% CI=0.45-1.49) or hospitalization (≥4 medications, OR=1.34, 95% CI=0.82-2.18, P =.24). There was also no association between PIM use and toxicity (P =.93) or hospitalization (P =.98). No medication class was associated with either outcome. Conclusions Polypharmacy and PIM use were common but were not associated with chemotherapy-related toxicity or hospitalization in older adults with cancer.