Examining factors associated with adherence to hormonal therapy in breast cancer patients

Breast cancer is a rampant disease and is highly prevalent among women in the United States. Two out of three breast cancers are hormone receptor positive and hormonal therapies (Tamoxifen and Aromatase Inhibitors) are used to treat this type of breast cancer. However, adherence to these efficacious therapies is relatively low.

The aim of this study was to identify factors that are associated with adherence to hormonal therapy among breast cancer patients, and the extent to which they influence adherence, by looking at data from a nationally representative database.

A retrospective cross-sectional study was conducted using Medical Expenditure Panel Survey (MEPS) for 2011-2015. Individuals ≥18 years diagnosed with breast cancer utilizing Tamoxifen and Aromatase inhibitors were identified. The Proportion of Days Covered (PDC) adherence measure was used to classify individuals as adherent (PDC≥80%) or non-adherent (PDC<80%). Multivariable logistic regression was used to determine factors associated with adherence to hormonal therapy.

Out of the 354 breast cancer respondents utilizing hormonal therapy, 194 (54.8%) were adherent and 160 (45.20%) were non-adherent. From 2011 through 2015, an increase in the usage of hormonal therapy was observed. Individuals having at least a high school diploma or General Equivalency Diploma (GED) had 2.795 (1.081, 6.941) times the odds of being adherent when compared to those who did not have a high school diploma or GED. Race, insurance status, marital status, poverty level, class of drug (aromatase inhibitor/tamoxifen), age, comorbidities, out-of-pocket costs and region were not significantly associated with adherence to hormonal therapy among breast cancer patients.

This study found an association between an individual's level of education and adherence to hormonal therapy among breast cancer patients. These results can be used to help optimize allocation of resources to promote knowledge designed to increase the adherence of breast cancer patients to hormonal therapy.