Abstract A076: Adherence to adjuvant endocrine therapy: Do racial disparities persist among the insured?

Purpose: Adjuvant endocrine therapy (AET) improves survival in women with hormone receptor-positive (HR+) breast cancer (BC). Yet medication adherence is suboptimal. The aim of this study was to assess adherence to AET among insured women using innovative statistical approaches.Methods: Black and White women diagnosed with HR+ BC were identified from two health maintenance organizations. Automated pharmacy records captured oral AET prescriptions and refill dates. Logistic regression identified predictors of adherence defined in terms of proportion of days covered (PDC) (>=80%) and medication gap of ≤10 days. A zero-inflated negative binominal (ZINB) regression model identified variables associated with the total number of days of medication gaps.Results: A total of 1,925 women met inclusion criteria. Eighty percent of women were adherent per the PDC measure; 44% had a medication gap of ≤10 days; and 24% of women had zero days without any medication gaps. Race and age were significant predictors of adherence in all multivariable models. Black women were less likely to have PDC >=80% than Whites (OR=0.72; 95%CI: 0.57-0.90; p<0.01), and they were less likely to have a medication gap of ≤10 days (OR=0.65; 95%CI: 0.54-0.79; p<0.001). Women 25-49 years old were less likely to have PDC >=80% than women 65-93 years old (OR=0.65; 95%CI: 0.48-0.87; p<0.001), and they also were less likely to have a medication gap of ≤10 days (OR=0.73; 95%CI: 0.57-0.93; p<0.01). In the zero-inflated negative binominal model, Black women were less likely to having no medication gaps compared to Whites (OR=0.46; 95%CI: 0.54-0.79; p<0.001), and women 25-49 years old were less likely to have no medication gaps compared to women 65-93 years old (OR=0.61; 95%CI: 0.42-0.88; p<0.01).Conclusions: Disparities in adherence to AET persist among insured women, particularly in Black and young women, highlighting a need for interventions among this population. Novel statistical approaches to study adherence, such as the ZINB approach, appear to constitute a useful alternative to the dichotomous PDC variable to tailor analysis to adherence patterns.Citation Format: Dennis Tolsma, Mahlet G. Tadesse, Arnethea Sutton, Lee Cromwell, Georges Adunlin, Teresa M. Salgado, Jun He, Martha Trout, Brandi E. Robinson, Megan C. Edmonds, Hayden B. Bosworth, Vanessa B. Sheppard. Adherence to adjuvant endocrine therapy: Do racial disparities persist among the insured? [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr A076.

Duke Scholars

Author Hayden Barry Bosworth Population Health Sciences