Relation of the CHA₂DS₂-VASc Score to Risk of Thrombotic and Embolic Stroke in Community-Dwelling Individuals Without Atrial Fibrillation (From The Atherosclerosis Risk in Communities [ARIC] Study)

Recent hospital-based cohort studies found the CHA₂DS₂-VASc score to be associated with ischemic stroke in individuals without atrial fibrillation (AF). Our aim was to determine the distribution of embolic and thrombotic strokes and association with the CHA₂DS₂-VASc score, among community-dwelling individuals without AF. We included participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended visit 4 (1996 to 1998) and had no previous AF, stroke, or anticoagulant use (n = 10,671). During follow-up through 2008, incident AF cases (n = 760) and participants who started warfarin were censored. Incident AF was ascertained from study electrocardiograms and hospital discharge diagnosis codes, and stroke was physician-adjudicated. After 10 years of follow-up, 280 ischemic strokes were identified, of which 146 were thrombotic and 57 embolic. The hazard ratios (95% confidence intervals [CI]) for thrombotic stroke were 1 (reference), 1.71 (1.13 to 2.59), 2.92 (1.91 to 4.45), 3.22 (1.70 to 6.11), and 1.25 (0.17 to 9.09), with CHA₂DS₂-VASc scores of 0 to 1, 2, 3, 4, and ≥5, respectively. The hazard ratios (95% CI) for embolic stroke were 1 (ref), 4.91 (2.10 to 11.5), 7.07 (2.93 to 17.0), 14.8 (5.50 to 39.6), and 15.2 (3.16 to 73.3), with CHA₂DS₂-VASc scores of 0 to 1, 2, 3, 4, and ≥5, respectively. A receiver-operating characteristic model had a C-statistic of 0.65 for ischemic stroke, 0.61 for thrombotic stroke, and 0.71 for embolic stroke. In conclusion, in community-dwelling individuals without AF, the CHA₂DS₂-VASc score can assess ischemic stroke risk and has good discriminatory capacity for embolic stroke.