Measures of polypharmacy and chemotherapy toxicity in older adults with cancer.
9545 Background: Polypharmacy is common and associated with adverse clinical outcomes in older adults. Potentially inappropriate medication (PIM) use serves as an adjunctive assessment of polypharmacy. The goals of this study in an outpatient population of older adults with cancer (CA) were: 1) to estimate the prevalence of polypharmacy using multiple measures; and 2) to determine the relationship between polypharmacy and chemotherapy (chemo) toxicity. Methods: Medication use was evaluated in 500 patients (pts) age ≥65 years with invasive CA who were starting a new chemo regimen. Polypharmacy was defined by number of daily medications (meds), including non-prescription meds. PIM use was defined by 4 indices: Beers (2003 and 2012 update), Zhan, and HEDIS Drugs to Avoid in the Elderly (DAE) criteria. Prevalence of polypharmacy, PIM, and their association with grade 3-5 chemo toxicity [NCI Common Toxicity Criteria (v. 3.0)] were analyzed using chi square test and unconditional logistic regression. Results: All 500 pts were evaluable [mean age, 73 years (range 65-91); 56% female; 61% stage IV]. The mean number of daily meds was 5 (range 0-23); 38% used ≤3 daily meds, 51% used 4-9 meds, and 11% using ≥10 meds. Using 0-3 daily meds as the referent group, no association was found between daily meds and chemo tox: 4-9 meds, OR 1.34 (95% CI: 0.92-1.97); ≥10, OR 0.82 (95% CI: 0.45-1.49). PIM use was identified in 87 (17%), 147 (29%), 54 (11%), and 69 (13%) patients utilizing the 2003 Beers, 2012 Beers, Zhan, and HEDIS DAE criteria, respectively. There was no association between each PIM use index and chemo toxicity (p>0.10 for all). Conclusions: Polypharmacy and PIM use were common in the geriatric oncology population. Although polypharmacy did not increase the risk of chemotherapy toxicity in this sample, further studies of polypharmacy’s impact on additional outcomes, including non-chemotherapy adverse drug events, in older persons with cancer are warranted.