Veterans Affairs Medical Center Racial and Ethnic Composition and Initiation of Anticoagulation for Atrial Fibrillation
Authors: Essien Utibe R. , Kim Nadejda , Hausmann Leslie R. M. , Washington Donna L. , Mor Maria K. , Litam Terrence M. A. , Boyer Taylor L. , Gellad Walid F. , Fine Michael J. 
Published: June 2024

ImportanceRacial and ethnic disparities exist in anticoagulation therapy for atrial fibrillation (AF). Whether medical center racial and ethnic composition is associated with these disparities is unclear.ObjectiveTo determine whether medical center racial and ethnic composition is associated with overall anticoagulation and disparities in anticoagulation for AF.Design, Setting, and ParticipantsRetrospective cohort study of Black, White, and Hispanic patients with incident AF from 2018 to 2021 at 140 Veterans Health Administration medical centers (VAMCs). Data were analyzed from March to November 2023.ExposureVAMC racial and ethnic composition, defined as the proportion of patients from minoritized racial and ethnic groups treated at a VAMC, categorized into quartiles. VAMCs in quartile 1 (Q1) had the lowest percentage of patients from minoritized groups (ie, the reference group).Main Outcomes and MeasuresThe odds of initiating any anticoagulant, direct-acting oral anticoagulant (DOAC), or warfarin therapy within 90 days of an index AF diagnosis, adjusting for sociodemographics, medical comorbidities, and facility factors.ResultsThe cohort comprised 89 791 patients with a mean (SD) age of 73.0 (10.1) years; 87 647 (97.6%) were male, 9063 (10.1%) were Black, 3355 (3.7%) were Hispanic, and 77 373 (86.2%) were White. Overall, 64 770 individuals (72.1%) initiated any anticoagulant, 60 362 (67.2%) initiated DOAC therapy, and 4408 (4.9%) initiated warfarin. Compared with White patients, Black and Hispanic patients had lower rates of any anticoagulant and DOAC therapy initiation but higher rates of warfarin initiation across all quartiles of VAMC racial and ethnic composition. Any anticoagulant therapy initiation was lower in Q4 than Q1 (69.8% vs 74.9%; adjusted odds ratio [aOR], 0.80; 95% CI, 0.69-0.92; P &amp;lt; .001). DOAC and warfarin initiation were also lower in Q4 than in Q1 (DOAC, 69.4% vs 65.3%; aOR, 0.85; 95% CI, 0.74-0.97; P &amp;lt; .001; warfarin, 5.4% vs 4.5%; aOR, 0.82; 95% CI, 0.67-1.00; P &amp;lt; .001). In adjusted models, patients in Q4 were significantly less likely to initiate any anticoagulant therapy than those in Q1 (aOR, 0.88; 95% CI, 0.78-0.99). Patients in Q3 (aOR, 0.75; 95% CI, 0.60-0.93) and Q4 (aOR, 0.69; 95% CI, 0.55-0.87) were significantly less likely to initiate warfarin therapy than those in Q1. There was no significant difference in the adjusted odds of initiating DOAC therapy across racial and ethnic composition quartiles. Although significant Black-White and Hispanic-White differences in initiation of any anticoagulant, DOAC, and warfarin therapy were observed, interactions between patient race and ethnicity and VAMC racial composition were not significant.Conclusions and RelevanceIn a national cohort of VA patients with AF, initiation of any anticoagulant and warfarin, but not DOAC therapy, was lower in VAMCs serving more minoritized patients.