h Estimate of the rate of nonfatal major extracranial bleeding on no therapy is derived from rates in observational cohorts of predominantly patients with AF receiving adjusted-dose VKA therapy (median, and dividing by the relative risk of major bleeding on adjusted-dose VKA therapy observed in the RCTs (see section of this article). i Quality of evidence is moderate for patients with a CHADS score of because the recommendation would differ if the true increase in nonfatal major extracranial bleeding was one vs bleeds per patients in a given year. j The CI does not exclude the possibility of no effect. k Based on rate of systemic embolism on aspirin of per patient-y reported in the IPD meta-analysis of warfarin vs aspirin by van Walraven et al and a relative risk of for aspirin vs no therapy for systemic embolism. www.chestpubs.org CHEST / 141 / 2 / FEBRUARY, 2012 SUPPLEMENT e541S 2.1.2 implies that adjusted-dose warfarin is far supe- rior to aspirin for the prevention of stroke in patients with AF but is likely to be associated with a greater risk of bleeding complications. 