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

Year 2026, Volume: 7 Issue: 1, 46 - 51, 20.02.2026

Aslı Gizem Tıraşçı Nur Düzen Oflas

https://izlik.org/JA33UC22FT

Abstract

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<0.001). They also demonstrated significantly lower glomerular filtration rate (37.9±9.3 vs. 59.6±22.9 ml/min/1.73m², p<0.001) and higher HbA1c levels (7.72±1.48% vs. 7.08±1.98%, p=0.021). Category C drug interactions were most common across all patients (91.9%), while category D interactions requiring therapy modification were significantly more prevalent in the multipolypharmacy group (57.9% vs. 24.6%, p=0.002).
Conclusion: DDIs are inevitable in polypharmacy. Patients using ≥10 medications demonstrate higher rates of chronic kidney disease and uncontrolled diabetes, with significantly increased prevalence of clinically significant drug interactions requiring therapeutic intervention. Regular medication review and monitoring are essential for elderly patients with polypharmacy.

Keywords

Polypharmacy , drug interactions , geriatric , chronic disease

Ethical Statement

ETHICS COMMITTEE APPROVAL REPUBLIC OF TÜRKİYE VAN YÜZÜNCÜ YIL UNIVERSITY NON-INTERVENTIONAL CLINICAL RESEARCH ETHICS COMMITTEE DECISION FORM FULL TITLE OF THE STUDY Prevalence and Clinical Outcomes of Drug–Drug Interactions in Patients Aged 65 Years and Older Admitted to Internal Medicine Outpatient Clinics: A Retrospective Analysis PRINCIPAL INVESTIGATOR Assist. Prof. Dr. Nur DÜZEN OFLAS Department of Internal Medicine Van Yüzüncü Yıl University Faculty of Medicine DECISION The above-mentioned study was reviewed by the Van Yüzüncü Yıl University Non-Interventional Clinical Research Ethics Committee. It was determined that the study complies with ethical standards and relevant regulations. The committee unanimously decided that there is no ethical objection to conducting this study. Decision No: 2025/08-39 Decision Date: 26/08/2025

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