Racial Disparity in Adherence to Endocrine Therapy among Women with Early-Stage Hormone Receptor Positive Breast Cancer: An Analysis of Arkansas All-Payers Claims Database.

Introduction/background: To assess racial/ethnic disparities in endocrine therapy (ET) adherence among women with breast cancer.

Materials And Methods: A retrospective cohort study of Arkansas All-Payer Claims Database (APCD) linked to Arkansas Cancer Registry (ACR). Women with stages 0-3 HR+ breast cancer diagnosed in 2013-2017 were followed from cancer diagnosis for a year to determine ET initiation. Among women who initiated ETs within 1 year of diagnosis, we assessed first-year compliance (proportion of days covered ≥ 0.8) and followed them for 5 years, censoring at death, end of data availability (December 21, 2019), or disenrollment from insurance coverage, whichever occurred first, to determine time to discontinuation. Regression analysis was conducted to determine racial/ethnic disparities in ET use adjusting for patients demographic, clinical, tumor characteristics and county-level socioeconomic factors.

Results: Among women with continuous insurance coverage, 81% initiated ET within 1 year of diagnosis; 80% were compliant in the first year of ET use and 27.4% discontinued ET by year 5 among those who initiated ET in the first year. There were no racial/ethnic differences in ET initiation or first-year compliance adjusting for covariates. NHB women were significantly less likely to discontinue ET within 5 years after ET initiation compared to NHW women after (HR, 95% CI, 0.76, 0.58-0.98; P = .035).

Conclusion: After adjusting for patients' and tumor characteristics, there were no racial/ethnic differences in ET initiation within 1 year of diagnosis and ET compliance within first year of ET use. However, NHB women were less likely to discontinue ET within 5 years of initiation.