F8 and Stroke: In addition, the prospective cohort study REasons for Geographic and Racial Differences in Stroke (REGARDS) showed that elevated FVIII level was associated with increased risk of IS during a 4.5-year follow-up [32] and also revealed that increased FVIII level was associated with IS risk in patients with atrial fibrillation during a 5.2-year follow-up [33].