Date of Award

May 2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Public Health Services

Committee Member

Rachel M Mayo

Committee Member

Windsor W Sherrill

Committee Member

Lori Dickes

Committee Member

Karyn Jones

Committee Member

Liwei Chen

Abstract

The aims of this study were to 1) describe endocrine therapy (ET) non-initiation, non-adherence, and duration by age, race, and temporal trend; 2) identify demographic, clinical, and pharmaceutical factors that are associated with an individual’s ET usage; and 3) understand from the survivor perspective which modifiable factors could have the greatest impact on the likelihood of ET continuation.

This study utilized a convergent parallel mixed methods design. The sample included female South Carolina (SC) residents ages 18-64 at diagnosis with hormone receptor-positive breast cancer. SC Central Cancer Registry incidence data linked with South Carolina Medicaid data (N=3,830) were along with focus groups in four SC locations (N=22). Age, race, relative risk and median duration of ET use were compared. Temporal trends in ET non-initiation, non-adherence, and duration were observed using linear and logistic regression models, controlling for age and race. A series of multiple regression models were built to explore the association of demographic, clinical, and pharmaceutical factors with ET usage duration. Qualitative data analysis was completed by a three-member research team using an inductive narrative approach. Themes were examined by participant decision to continue or discontinue ET.

Fifty three percent of women in the sample did not initiate ET, with highest non-initiation rates among African Americans and survivors under age 50. Of those who did initiate ET, 42% were non-adherent with a median ET usage duration of 37 months. Twenty one percent of initiators continued taking ET for five years or more. There was no change in the odds of ET non-initiation from 2000 – 2004. The odds of ET non-initiation decreased from 2005 – 2009 but then increased from 2010 – 2014. There was no change in the odds of ET non-adherence from 2000 – 2006, but from 2007 – 2012, the odds of ET non-adherence decreased each year. The average ET usage duration was increasing from 2000 – 2006 but decreasing from 2006 – 2012.

Multiple linear regression analysis showed that none of the demographic or clinical factors tested were significantly associated with ET usage duration. The type of ET taken as well as receipt of the prescriptions that could have been used to alleviate side effects were significantly associated. Participants’ feedback centered on a risk vs. benefit analysis unique to the individual survivor. Main themes included the importance of an open, honest patient/provider relationship and the need for personal information seeking and affirmation in the decision to take ET. There was clear support for the utility of multidisciplinary cancer care teams and incorporating integrative approaches.

This study provides a realistic picture of the challenges associated with ET usage among South Carolina Medicaid breast cancer patients. It particularly highlights more opportunity for improvement in ET initiation, adherence, and duration among younger women of lower socioeconomic status. Our study also highlights the potential value of concurrent prescriptions for improving ET usage duration, with an optimal intervention point before 14 months post ET initiation. Further research is needed to test pharmacologic interventions that may significantly increase ET duration as well as other non-pharmacologic strategies for side effect management. Research employing patient-centered perspectives is imperative. Novel and practical patient-centered interventions in research exploring openness in the patient/provider relationship, survivor information seeking practices, multidisciplinary teams, and integrative approaches are needed.

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