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

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.

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.

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).

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.