Potential drug-drug interactions among geriatric oncology patients: a retrospective study in Saudi Arabia.

Background: Drug-drug interactions (DDIs) are significant causes of adverse drug reactions among patients with cancer. We aimed to identify the prevalence, severity, and predictors of potential DDIs among geriatric oncology patients.

Methods: A cross-sectional, retrospective study was conducted at two tertiary medical centers. Geriatric patients (≥ 65 years) who were diagnosed with solid tumors and received outpatient prescriptions with a minimum of two drugs between January 2018 and December 2022 were included in the study. Patients' medications were screened for DDIs using Lexi-Interact. Univariate and multivariable logistic regression models were used to explore factors associated with DDIs.

Results: The study included 247 geriatric patients with a mean age of 74.0 ± 7.3 years, and 48.6% of the patients were female. The most common type of cancer was gastrointestinal cancer (35.6%), followed by genitourinary cancer (20.6%), and 50.6% of the patients had metastasized tumors. Approximately one-half of the patients (49.0%) received anticancer therapy, and hormonal therapy (21.9%) or chemotherapy (16.6%) was the most common therapy. The mean number of medications used per patient was 6.9 ± 3.5. The majority of patients (79.4%) had at least one DDI, with a mean of 5.6 ± 5.3 DDIs per patient. Most of the interactions were classified as moderate (58.9%), and only 19.3% were classified as major. Multiple logistic regression revealed that females were more vulnerable to DDIs than their male counterparts were (adjusted odds ratio (AOR) = 37.4; 95% CI 4.13-338.3). The number of medications used was significantly associated with the risk of DDIs (AOR = 4.07; 95% CI 2.53-6.54). Compared with patients with gastrointestinal cancers, patients with breast or gynecologic cancers had lower odds of experiencing DDI (AOR = 0.02; 95% CI < 0.01-0.24 and AOR = 0.04; 95% CI < 0.01-0.29, respectively).

Conclusion: This study revealed a high prevalence of DDIs among geriatric oncology patients, with most interactions classified as moderate. Female patients and patients taking multiple medications had a greater risk of experiencing DDIs. Routine screening for potential DDIs is essential for this vulnerable population, and the factors identified in this study should be carefully considered.