c 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 ). d Intracranial hemorrhage includes intracerebral, subdural, and subarachnoid bleeds. For SPAF II, which did not report the number of strokes that were fatal and nonfatal, we imputed values for the number of fatal and nonfatal strokes to estimate the pooled relative risk for nonfatal stroke across all eligible studies. Assumptions underlying these estimates are detailed in section of this article. e Of the nonfatal strokes on antiplatelet therapy, an estimated were ischemic, and seven were hemorrhagic. f Of the nonfatal strokes on VKA therapy, an estimated were ischemic, and were hemorrhagic. g We estimated the annual rates of nonfatal stroke (ischemic and hemorrhagic) on no therapy 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. h The CI does not exclude appreciable harm with VKA therapy. i Rates of nonfatal major extracranial bleeding on aspirin are extrapolated from rates observed in observational cohorts of patients receiving adjusted-dose VKA therapy (median, and relative risks of major extracranial bleeding associated with VKA therapy (RR, and aspirin (RR, compared with no therapy. j The CI does not exclude the possibility of appreciable bene t or harm with VKA therapy. k Based on rate of systemic embolism on aspirin of per patient-y reported in the individual patient data meta-analysis of warfarin vs aspirin by van Walraven et al. 