OP3-2 - Disparities in the uptake of newer anticoagulant therapies for atrial fibrillation by race, ethnicity and social vulnerability in Medicare fee-for-service data

Background:  Atrial fibrillation – a frequently occurring condition characterized by substantial morbidity and mortality – disproportionally affects racial and ethnic minorities. For decades warfarin has been the drug of choice for atrial fibrillation, but direct-acting oral anticoagulants (DOACs) are now increasingly recommended by clinical guidelines owing to their convenience, safety, and effectiveness profiles. However, there is a paucity of data on the uptake of these newer therapies among subgroups of race, ethnicity, or social determinants of health (SDoH).

Objective:  To evaluate the disparities in the uptake of newer DOACs among subgroups of race, ethnicity, and SDoH.

Methods:  This was a retrospective, serial cross-sectional study using a 50% random sample of Medicare fee-for-service data from 2010 to 2019. We identified older adults (≥65 years) with atrial fibrillation newly initiating either warfarin or DOACs (dabigatran, rivaroxaban, apixaban, and edoxaban). Patients were classified into the following race and ethnicity categories: non-Hispanic White (“White”), Black race, Hispanic ethnicity, and other race. The CDC/ATSDR Social Vulnerability Index (SVI) was used to ascertain county-level SDoH information on the following four domains: (i) Socioeconomic status, (ii) Household composition and disability, (iii) Minority status & language, and (iv) Housing & transportation. We modeled the relative risks of initiating DOACs (vs warfarin), adjusting for the effects of race and ethnicity, age, sex, SVI themes, and other characteristics. Models were estimated by calendar year as well as over the study period.

Results:  We identified 2,491,452 eligible episodes of anticoagulation initiation among older adults (median age [interquartile range (IQR)]: 77 (72-83) years; 42.9% male). Over the study period, compared to White patients, Black patients were 32.8% less likely to initiate DOACs: adjusted relative risks [RR (95% confidence interval)]: 0.67 (0.66, 0.68). In 2010, when DOACs were first introduced, Black patients were 64.4% less likely to initiate DOACs, RR: 0.36 (0.29 0.43). However, this difference continued to diminish yearly over the course of the study period, declining from 64.4% in 2010 to 36.7% in 2015 and reaching 6.7% (2.2,11.1) in 2019. These disparities were not evident for other racial and ethnic minorities. Notably, SDoH (including socioeconomic status and other SVI themes) was not found to be a major determinant of the choice of anticoagulant initiated.   

 


Conclusion: Disparities in the use of newer (and guideline-recommended) anticoagulation therapies were most evident for Black patients, though these differences diminished over the course of the study period. Such disparities were not evident in other racial and ethnic minorities nor across pertinent SDoH categories. Understanding the reasons for these disparities in medication use is necessary to promote equitable management of atrial fibrillation and outcomes among older Black patients in the US.