A cross-sectional observational study of the prevalence and characterization of potential QT-prolonging drug‒drug interactions in oncological outpatients.

This study aims to assess the prevalence, characteristics, and risk factors of potential QT-prolonging drug-drug interactions (pQT-DDIs) in cancer patients, including identifying drug combinations contributing to QT prolongation and key predictors. In this hospital-based, cross-sectional observational study, all types of cancer patients, irrespective of age or sex, were included over 1 year. pQT-DDIs were identified using four drug interaction checker software tools. Predictors were analyzed using univariate logistic regression. A total of 1,331 cancer patients were included. The prevalence of pQT-DDIs was 67.6 %. Of these, 606 (45.5 %) had 1-2 pQT-DDIs, 126 (9.5 %) had 3-4, and 78 (5.9 %) had 5-6. Overall, 163 drug combinations were identified as causing QT prolongation; 122 were detected by Drugs.com. Significant predictors included >8 drugs prescribed (OR=6.46; CI=4.87-8.56; p<0.0001), >2 anticancer drugs (OR=1.68; CI=1.14-2.46; p=0.008), >6 adjuvant drugs (OR=6.83; CI=5.17-9.03; p<0.0001), solid cancers (OR=6.59; CI=4.59-8.80; p<0.0001), and cytotoxic drug use (OR=2.40; CI=1.52-3.77; p=0.0001). There is a high prevalence of pQT-DDIs in cancer patients. Those receiving multiple anticancer and adjuvant drugs are at higher risk. Routine interaction screening is recommended before chemotherapy.