Potentially inappropriate medication (PIM) use and severe drug interactions (SDIs) in older adults with cancer

Background: Older adults with cancer frequently have other co-morbidities requiring prescription pharmacotherapy. The objectives of this study were to identify the prevalence of potentially inappropriate medications (PIMs), severe drug interactions (SDIs) and associated risk factors in these patients.

Materials and methods: This twelve-month prospective observation study was conducted at an Irish Hospital. PIMs were identified in older adults (≥65 years) using STOPP and OncPal criteria; potential SDIs using Stockley's interaction checker.

Results: We enrolled 186 patients; mean age 72.5(SD5.7) years, 46.2% female, mean co-morbidities 7.5(SD3.4), median medications 7(IQR4-9). Polypharmacy (≥6 medications) and major polypharmacy (≥11 medications) were identified in 60.8% and 17.7% respectively. STOPP PIMs were observed in 73.1%; median 2(IQR1-3). The most common PIM identified was any drug prescribed beyond the recommended duration (46.5%). For each additional prescription, the odds of receiving a STOPP PIM increased by 79.2% (OR 1.792, 95% CI 1.459-2.02). Potential SDIs were identified in 50.5% participants. The most common were beta-blocker/alpha-blocker (6.5%), selective-serotonin re-uptake inhibitor (SSRI)/proton pump inhibitor (PPI) (5.9%) and SSRI/Aspirin (4.8%). For each additional prescription, the odds of an SDI increased by 50.8% (OR 1.508, 95% CI 1.288-1.764). Seventy-seven (41.4%) participants died within six months of enrolment. OncPal PIMs were observed in 81.8% of this cohort, median 2(IQR1-3). The most common OncPal PIM was statin therapy (38%). For each additional prescription, the odds of receiving an OncPal PIM increased by 38.2%, (OR 1.382, 95% CI 1.080-1.767).

Conclusions: PIMs and SDIs are common in this population. Comprehensive specialist evaluation of medications by a geriatrician may identify PIMs thereby reducing related adverse outcomes such as SDIs.