Abstract PD4-02: Health beliefs predict adherence to aromatase inhibitors
Authors: Brier MJ , Stricker CT , Chambless DL , Chen J , Ahluwalia K , Mao JJ 
Published: May 2016

Background: Post-menopausal breast cancer survivors are often prescribed aromatase inhibitors (AIs) to decrease the chance of cancer recurrence. Despite their efficacy, many survivors do not fully adhere to their AI regimen. To improve adherence rates, it is important to understand which patient factors are associated with adherence. Current research has mostly focused on demographic, cancer, and symptom variables, most of which cannot be modified. One relevant factor that may be modifiable is health beliefs, which include perceived susceptibility of cancer recurrence, perceived benefits of treatment, and perceived barriers to treatment. Among breast cancer patients, each of these has been found to be associated with adherence behaviors, such as mammography and tamoxifen adherence. In this study, we explored whether health beliefs also play a role in adherence to AIs. Objective: The purpose of this longitudinal study was to determine whether patients with lower perceived susceptibility to cancer recurrence, higher perceived barriers to taking AIs, and lower perceived benefits of AIs were more likely to non-adhere to their AI regimen. Method: Four hundred and thirty-seven breast cancer survivors who were currently on an AI completed a survey that included the Health Beliefs and Medication Adherence in Breast Cancer (HBMABC) scales (a measure adapted from the Champion Health Belief Model Scales (CHBMS) for Mammography Screening), as well as questions about their demographics and symptoms. Exploratory and confirmatory factor analysis of the HBMABC yielded a 3-factor solution: perceived susceptibility, perceived benefits, and perceived barriers. Adherence data, including drug holidays (taking breaks from AI treatment) and premature discontinuation (stopping AI treatment early), were collected from physicians' notes in patients' medical charts dating from the day they completed the survey through the end-date of their prescribed AI treatment. Bivariate analyses were conducted to determine variables that were predictive of non-adherence. Variables found to be associated with non-adherence were entered into multiple logistic regression analyses. Results: Eighty-five patients (20.6%) exhibited some form of non-adherence (premature discontinuation, drug holiday, or both). Joint pain severity and the number of years a patient was on an AI at the time of the survey were both associated with non-adherence. After adjusting for these covariates, perceived barriers to AI treatment was significantly associated with non-adherence (OR 1.76, 95% CI: 1.03 – 3.00, p = 0.04). No relationship was found between perceived susceptibility or perceived benefits, and AI adherence. Conclusions: Breast cancer patients on AIs who perceive greater barriers to AI treatment are more likely to non-adhere to their AI regimen. This finding suggests that clinicians can intervene to help modify patients' negative beliefs and ultimately help improve patients' adherence levels.

Citation Format: Brier MJ, Stricker CT, Chambless DL, Chen J, Ahluwalia K, Mao JJ. Health beliefs predict adherence to aromatase inhibitors. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD4-02.