Prevalence and Factors Associated with Drug-Drug Interactions among Elderly Cancer Patients in a University Hospital

Abstract

Objective: To investigate the prevalence, severity, and factors associated with drug-drug interactions (DDIs) among elderly cancer patients receiving chemotherapy. Methods: This retrospective cross-sectional study was conducted among 390 patients aged 65 years and older at Srinagarind Hospital between January 1 and December 31, 2023. The study retrieved medication data from electronic medical records and identified DDIs using information from the Lexicomp® database and the 2023 American Geriatrics Society (AGS) Beers Criteria®. Results: The prevalence of potential DDIs according to the Lexicomp® database was 97.4%, whereas potentially inappropriate drug combinations identified using the Beers Criteria® accounted for 23.8%. Multivariable logistic regression analysis identified factors significantly associated with the presence of potential DDIs based on the Lexicomp® database including concurrent use of ten or more medications (aOR 18.04, 95% CI: 6.05–53.86, P<0.001), metastatic cancer stage (aOR 1.88, 95% CI: 1.18–3.00, P=0.008), gynecologic malignancy (aOR 3.59, 95% CI: 1.65–7.80, P=0.001) and other cancer types (aOR 5.26, 95% CI: 1.96–14.16, P=0.001). Most DDIs were classified as Risk C interactions (56.5% of unique interacting drug pairs). Conclusion: Elderly cancer patients receiving chemotherapy demonstrated a high prevalence of potential DDIs. Number of medications received by patients was significantly associated with an increase in potential DDIs. Therefore, pharmacists should play an active role in systematically reviewing medication and monitoring potential DDIs in collaboration with a multidisciplinary healthcare team to enhance medication safety for patients.