Oral Endocrine Therapy Agent, Race/Ethnicity, and Time on Therapy Predict Adherence in Breast Cancer Patients in a Large Academic Institution

To objectively assess medication adherence to oral endocrine therapy in breast cancer patients, we accessed refill data through the electronic health records (EHR) of 338 patients. Race/ethnicity, type of endocrine therapy, and time on therapy were significantly associated with adherence in a multivariate analysis. Our study highlights EHR as a source of patient data for assessing medication adherence and its predictors. Introduction: Adherence to oral endocrine therapy (OET) reduces recurrence risk for hormone receptor (HR)-positive breast cancer (BC). Refill data accessed through electronic health records may provide objective assessment of OET adherence. Our goal was to (1) determine the feasibility of reviewing electronic health records for assessing OET adherence, (2) evaluate 6 months' OET adherence in HR-positive BC patients, and (3) identify predictors of low adherence. Patients and Methods: A single-center, retrospective study from May through December 2018 was conducted. Primary end point was adherance rate at 6 months. Chi-square and Student t tests were used to compare adherent and nonadherent groups. Multivariable logistic regression models were used to assess predictors of adherence. Results: Of 492 patients, 338 patients were included in adherence analysis. Of 338 patients identified, 82% (n - 277) were adherent at 6 months. In the multivariable logistic model, race/ethnicity, type of endocrine therapy, and time on therapy were found to be significantly associated with adherence. Asian/non-Hispanic and white/Hispanic patients were less likely to be adherent compared to white/non-Hispanics (Asian/non-Hispanic: odds ratio [OR], 0.3; 95% confidence interval [CI], 0.11-0.82; white/Hispanic: OR, 0.27; 95% CI, 0.11-0.64). Patients prescribed aromatase inhibitors were more likely to be adherent compared to patients prescribed tamoxifen (OR, 2.06; 95% CI, 1.02-4.14). Last, patients prescribed OET for 3 to 5 years had lower adherence compared to patients given OET for 2 years or less (OR, 0.29; 95% CI, 0.09-0.91). Conclusion: Accessing refill data through electronic health records was found to be feasible. Tamoxifen therapy, Asian/non-Hispanic and white/Hispanic origin, and longer time on therapy predicted nonadherence in our patients. (C) 2020 Elsevier Inc. All rights reserved.