a The CI does not exclude the possibility of no effect. b Based on data from Go et al, which reported a mortality rate of per person-y in untreated (no warfarin) patients from an observational study (ATRIA cohort) and an estimated relative risk of mortality of for aspirin vs no therapy ( Table ). c Hemorrhagic stroke not clearly de ned in published RCT report (ie, unclear whether subdural and subarachnoid bleeds were included in the de nition of hemorrhagic stroke). d The published RCT report did not present the proportion of nonfatal strokes in the aspirin arm that were ischemic vs hemorrhagic; however, of all strokes (fatal and nonfatal), were hemorrhagic, and were ischemic or of uncertain type. e The published RCT report did not present the proportion of nonfatal strokes in the combination aspirin clopidogrel arm that were ischemic vs hemorrhagic; however, of all strokes (fatal and nonfatal), were hemorrhagic, and were ischemic or of uncertain type. f We estimated the annual rates of nonfatal stroke (ischemic and hemorrhagic) on aspirin by extrapolating from observed annual rates of ischemic stroke (fatal nonfatal), strati ed by CHADS score, in the aspirin arms of six historical RCTs in patients with AF (Gage et al ). Assumptions underlying these estimates are detailed in section of this article. g The published report did not provide the number of major extracranial bleeds that were fatal and nonfatal; therefore, we imputed values for the number of fatal and nonfatal major extracranial bleeds to estimate the relative risk for nonfatal major extracranial bleeds. Assumptions underlying these estimates are detailed in section of this article. 