Potential drug-drug interactions and risk of unplanned hospitalization in older patients with cancer: A survey of the prospective ELCAPA (ELderly CAncer PAtients) cohort.

Background: Because of comorbidities and polypharmacy, older patients with cancer have a greater risk of iatrogenic events. We aimed to characterize potential drug-drug interactions (PDIs) and the risk of unplanned hospitalization in older patients with cancer treated with antineoplastic agents (ANAs).

Methods: We analyzed all older patients (≥70 years) from the prospective ELCAPA cohort referred for geriatric assessment (2007-2014) prior to treatment with ANA at Henri Mondor Hospital (Créteil, France). PDIs were identified using Lexicomp®, and Theriaque® for French medications. Factors associated with PDIs, and association between PDIs and unplanned hospitalization in the 6 months following geriatric assessment were analyzed using ordered multivariate logistic regression (MLR).

Results: We included 442 patients (median [interquartile range] age: 77 years [74-80]); number of medications/patient/day: 6 [3-8]); ECOG-PS ≤ 2: 79%; metastasis: 70%). Most patients had a digestive tract cancer (colorectal: 22%; upper digestive tract: 23%). We identified 1742 PDIs; 76.5% of patients had ≥1 PDI; 13% of the PDIs involved an ANA. In a multivariate analysis, cardiovascular disorders (ischemic heart disease, heart failure, atrial fibrillation and/or arterial hypertension) were independently associated with PDIs (p < .001, after adjustment for polypharmacy and tumor site/stage). A high number of PDIs between two daily medications was independently associated with the risk of unplanned hospitalization (adjusted-odds ratio [95% confidence interval] per PDI: 1.05 [1.00;1.11], p = .05), while polypharmacy was not.

Conclusion: Patients with cardiovascular comorbidities were more likely to have a PDI. A higher number of PDIs may be an independent risk factor for early unplanned hospitalization.