CHA₂DS₂-VASc Score and Stroke Prediction in Atrial Fibrillation in Whites, Blacks, and Hispanics

Background and Purpose - Despite modest predictive ability for ischemic stroke (IS), the CHA₂DS₂-VASc score is widely used for stroke prediction in atrial fibrillation. Among patients with atrial fibrillation, we aimed to (1) compare the IS or transient ischemic attack (TIA) incidence by CHA₂DS₂-VASc in blacks and Hispanics versus whites; (2) compare predictive ability of CHA₂DS₂-VASc score for IS or TIA in blacks and Hispanics versus whites; and (3) determine improvement in predictive ability of CHA₂DS₂-VASc score from addition of race/ethnicity. Methods - Using data from Optum Clinformatics, a large administrative claims database, we analyzed patients with atrial fibrillation enrolled in commercial and Medicare Advantage health plans from 2009 to 2015. We computed IS or TIA incidence rates, improvement in C statistic, continuous and categorical net reclassification improvement, and relative integrated discrimination improvement from addition of race/ethnicity to CHA₂DS₂-VASc. Results - A total of 267 419 patients (mean age, 73.1 [SD, 12.3] years; 46.6% women; 84.2% white, 8.5% black, 7.3% Hispanic) were studied. After a mean follow-up of 22 months, there were 6202 IS or TIA events. IS or TIA incidence rates were higher in blacks than Hispanics or whites (1.65, 1.40, and 1.22 cases per 100 person-years, respectively) and increased with higher CHA₂DS₂-VASc, with no race/ethnicity-based differences (P for interaction=0.17). The CHA₂DS₂-VASc and CHA₂DS₂-VASc+race/ethnicity C statistic (95% CI) were 0.679 (0.670-0.686) and 0.679 (0.671-0.688). The CHA₂DS₂-VASc C statistic in the 3 groups were comparable. With addition of race/ethnicity, the categorical net reclassification improvement, continuous net reclassification improvement, and relative integrated discrimination improvement were -0.045 (95% CI, -0.067 to -0.025), 0.045 (95% CI, 0.025-0.068), and 0.016 (95% CI, 0.014-0.018). Conclusions - The predictive ability of CHA₂DS₂-VASc for IS or TIA in atrial fibrillation is comparable among whites, blacks, and Hispanics; hence, it can be used in the latter 2 groups. Addition of race/ethnicity to the CHA₂DS₂-VASc does not improve its predictive ability.