Adding ethnicity to the CHA2DS2-VASc score for patients older than 65 years of age with newly diagnosed atrial fibrillation (AF) significantly improved stroke prediction, according to recent data published in the Journal of the American College of Cardiology.
Rajesh Kabra, MD, of the University of Tennessee Health Science Center, and colleagues studied the addition of African-American ethnicity to the CHA2DS2-VASc score, which currently includes risk factors like congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke, vascular disease, age 65 to 74, and female sex.
Medicare claims identified 460 417 patients with newly diagnosed AF between January 2010 and December 2012. CHA2DS2-VASc was calculated “on the basis of diagnoses in claims incurred during 12 months before first AF diagnosis.” In addition, researchers calculated a CHA2DS2-VASc-R score by assigning 1 additional point for African-American ethnicity.
The primary outcome was stroke, which was defined as a primary diagnosis on an acute inpatient admission after the initial AF diagnosis.
“This improvement in stroke prediction persisted across all CHA2DS2-VASc scores even after adjustment for anticoagulation use,” the authors concluded. “Moreover, in analysis of individual patient factors in the CHA2DS2-VASc-R score, we found that only 3 factors (history of stroke, age ≥75 years, and female sex) were stronger predictors of stroke than African-American ethnicity.”
Of the 460 417 patients (mean age: 79.2 ± 8.0 years; 60% female) with AF that were included in the study, 85% were non-Hispanic whites, 7% were non-Hispanic African Americans, and the remainder were additional non-white ethnicities.
A total of 16 703 stroke events occurred and 151 441 (32.7%) patients died after a mean follow-up period of 18 months. Researchers also found that the CHA2DS2-VASc-R score improved the scoring model significantly, as measured by the log likelihood ratio statistic (P<.001).
The authors noted that the prevalence of AF in African Americans is significantly lower than among white individuals. “Possible explanations include genetics and smaller left atrial sizes in African Americans that protect against AF. AF development and progression may therefore follow different patterns and consequences in African American than white patients,” they wrote.
“Although there is a need to systematically study and address each of these possibilities that potentially increase the risk of stroke in African Americans with AF, there is enough evidence to suggest that African-American ethnicity is a predictor of stroke in AF patients.”
Additional studies are necessary to evaluate the impact of African-American ethnicity on stroke risk among young individuals, and to clarify the mechanisms that link ethnicity to clinical outcomes.
Kabra R, Girotra S, Sarrazin MV. Refining stroke prediction in atrial fibrillation patients by addition of African-American ethnicity to CHA2DS2-VASc score. J Am Coll Cardiol. 2016;66(5): doi: 10.1016/j.jacc.2016.05.044.