Wayneho Kam, MD
Sur NB, Wang K, Di Tullio MR, Gutierrez CM, Dong C, Koch S, et al. Disparities and Temporal Trends in the Use of Anticoagulation in Patients With Ischemic Stroke and Atrial Fibrillation. Stroke. 2019;50:1452-1459.
Race-ethnic and sex disparities in stroke incidence and stroke-related death and disability are well-documented and persist in the modern health care system. The factors that contribute to these disparities are many, and stem from the biosocial complexities of the disease and the prevailing inequalities that exist in the continuum of stroke care.
The study by Sur et al., published in the June issue of Stroke, sought to examine yet another potential disparity in stroke care: differences in oral anticoagulant prescription pattern between blacks vs whites and women vs men for secondary stroke prevention. Data was drawn from the Florida-Puerto Rico Collaboration to Reduce Stroke Registry, which included 24040 patients with ischemic stroke and atrial fibrillation (AF).
The authors of the study found that from 2010 to 2016, the use of direct oral anticoagulants (DOACs) increased from 0% to 36%, with warfarin use decreasing from 51% to 17% and aspirin use remaining relatively stable. This is an unsurprising trend given that multiple trials have shown DOACs to be equivalent or superior to warfarin in the prevention of stroke among patients with nonvalvular AF, with a potential lower risk of bleeding. However, despite this known benefit, the present study found that blacks were still more likely to be discharged on warfarin compared to whites after their ischemic strokes (OR, 1.22; 95% CI, 1.07-1.40; P=0.004). Fewer blacks were placed on DOACs at discharge than whites (18.4% vs 19.5%), though this difference did not reach statistical significance. Compared with men, women had lower odds of being discharged on aspirin (OR, 0.92; 95% CI, 0.86-0.98; P=0.007) and warfarin (OR, 0.91; 95% CI, 0.84-0.99; P=0.03); however, no difference was seen in DOAC prescription at discharge between women and men (OR, 0.96; 95% CI, 0.86-1.07; P=0.45).
There were several limitations in the present study. While multivariate regression analyses were performed adjusting for age, insurance status, stroke severity, stroke risk, renal function, and hospital academic status, additional unaccounted factors exist that could have influenced the observed prescription pattern seen here. Patient preference, cost of copay, prior anticoagulation use, and stroke etiology (e.g., valvular disease, antiphospholipid syndrome) are some of the potential confounding variables that may have influenced the selection of the anticoagulant, though these elements were not explicitly recorded in the registry.
It is also interesting to note that 7.3% of whites, 2.8% of blacks, 13% of women, and 3% of men were not started on aspirin, warfarin, or a DOAC at the time of their discharge. It is unclear if these patients were placed on a different antithrombotic therapy (clopidogrel, enoxaparin) or had an apparent contraindication to taking such medications. Determining the reason for why more women and more whites were seemingly not started on any antithrombotic medication for stroke prevention is an equally important question to address.
It is an unfortunate well-established observation that the burden of cerebrovascular disease disproportionately affects minorities and disadvantaged populations. Future studies should include the aforementioned missing elements of the current study so that we are better able to explain the factors that drive the disparities in stroke care. A follow-up study that assesses the prescription patterns of antithrombotic therapy in a post-discharge stroke clinic may prove to be useful, as usage patterns may be somewhat different in this setting.