Polypharmacy, Inappropriate Medication Use, and Drug Interactions in Older Korean Patients with Cancer Receiving First-Line Palliative Chemotherapy

Polypharmacy is an important issue in the care of older patients with cancer, as it increases the risk of unfavorable outcomes. We estimated the prevalence of polypharmacy, potentially inappropriate medication (PIM) use, and drug-drug interactions (DDIs) in older patients with cancer in Korea and their associations with clinical outcomes. This was a secondary analysis of a prospective observational study of geriatric patients with cancer undergoing first-line palliative chemotherapy. Eligible patients were older adults (≥70 years) with histologically diagnosed solid cancer who were candidates for first-line palliative chemotherapy. All patients enrolled in this study received a geriatric assessment (GA) at baseline. We reviewed the daily medications taken by patients at the time of GA before starting chemotherapy. PIMs were assessed according to the 2015 Beers criteria, and DDIs were assessed by a clinical pharmacist using Lexi-comp Drug Interactions. We evaluated the association between polypharmacy and clinical outcomes including treatment-related toxicity, and hospitalization using logistic regression and Cox regression analyses. In total, 301 patients (median age 75 years; range, 70-93) were enrolled; the most common cancer types were colorectal cancer (28.9%) and lung cancer (24.6%). Mean number of daily medications was 4.7 (±3.1; range, 0-14). The prevalence of polypharmacy (≥5 medications) was 45.2% and that of excessive polypharmacy (≥10 medications) was 8.6%. PIM use was detected in 137 (45.5%) patients. Clinically significant DDIs were detected in 92 (30.6%) patients. Polypharmacy was significantly associated with hospitalization or emergency room (ER) visits (odds ratio: 1.73 [1.18-2.55], p < .01). Neither polypharmacy nor PIM use showed association with treatment-related toxicity. Polypharmacy, PIM use, and potential major DDIs were prevalent in Korean geriatric patients with cancer. Polypharmacy was associated with a higher risk of hospitalization or ER visits during the chemotherapy period. This study, which included 301 older Korean patients with cancer, highlights the increased prevalence of polypharmacy in this population planning to receive palliative chemotherapy. The prevalence of polypharmacy and excessive polypharmacy was 45.2% and 8.6%, respectively. The prescription of potentially inappropriate medications (PIMs) was detected in 45.5% and clinically significant drug-drug interaction in 30.6% of patients. Given the association of pol