Prevalence and clinical impact of drug–drug interactions in geriatric patients with polypharmacy

Aims: This study aimed to determine the prevalence and severity of drug-drug interactions (DDIs) and their clinical outcomes in patients aged 65 years and above with polypharmacy attending internal medicine outpatient clinics. Methods: A retrospective analysis was conducted on patients aged 65 and over who visited the Internal Medicine Outpatient Clinic at Van Yüzüncü Yıl University Medical Center between June 1, 2024, and February 1, 2025. Patients using ≥5 medications for chronic diseases (excluding those with active malignancy or on routine hemodialysis) were included. DDIs were evaluated using the Lexicomp® Drug Interactions Database and classified into risk categories A, B, C, D, and X. Clinical and laboratory parameters were compared between polypharmacy (5-9 drugs) and multipolypharmacy (≥10 drugs) groups. Results: A total of 259 patients were included (mean age: 72.8±6.3 years; 55.2% female). The most prevalent chronic conditions were hypertension (95.4%), coronary artery disease (76.1%), and diabetes mellitus (61.8%). Patients in the multipolypharmacy group had significantly higher rates of coronary artery disease (100% vs. 74.2%, p=0.011) and chronic kidney disease (89.5% vs. 34.6%, p