Association of polypharmacy and potential drug‐drug interactions with adverse treatment outcomes in older adults with advanced cancer

Background Polypharmacy is common in older adults who are starting cancer treatment and is associated with an increased risk of potentially inappropriate medications (PIMs) and potential drug‐drug interactions (PDIs). The authors evaluated the association of medication measures with adverse outcomes in older adults with advanced cancer who were receiving systemic therapy. Methods This secondary analysis from GAP 70+ Trial (ClinicalTrials.gov identifier NCT02054741; principal investigator, Supriya G. Mohile) enrolled patients aged 70 years and older with advanced cancer who planned to start a new treatment regimen (n = 718). Polypharmacy was assessed before the initiation of treatment and was defined as the concurrent use of eight or more medications. PIMs were categorized using 2019 Beers Criteria and the Screening Tool of Older Persons' Prescriptions. PDIs were evaluated using Lexi‐Interact Online. Study outcomes were assessed within 3 months of treatment and included: (1) the number of grade ≥2 and ≥3 toxicities according to the National Cancer Institute Common Toxicity Criteria, (2) treatment‐related unplanned hospitalization, and (3) early treatment discontinuation. Multivariable regression models examined the association of medication measures with outcomes. Results The mean patient age was 77 years, and 57% had lung or gastrointestinal cancers. The median number of medications was five (range, 0–24 medications), 28% of patients received eight or more medications, 67% received one or more PIM, and 25% had one or more major PDI. The mean number of grade ≥2 toxicities in patients with polypharmacy was 9.8 versus 7.7 in those without polypharmacy (adjusted β = 1.87; standard error, 0.71; p