Aspirin significantly reduced incidence of nonfatal myocardial infarction ( 0.30 [ 95 % CI , 0.19-0 .47 ] for aspirin vs 0.58 [ 95 % CI , 0.42-0 .81 ] for no aspirin ; HR , 0.53 [ 95 % CI , 0.31-0 .91 ] ; P = .02 ) and transient ischemic attack ( 0.26 [ 95 % CI , 0.16-0 .42 ] for aspirin vs 0.49 [ 95 % CI , 0.35-0 .69 ] for no aspirin ; HR , 0.57 [ 95 % CI , 0.32-0 .99 ] ; P = .04 ) , and significantly increased the risk of extracranial hemorrhage requiring transfusion or hospitalization ( 0.86 [ 95 % CI , 0.67-1 .11 ] for aspirin vs 0.51 [ 95 % CI , 0.37-0 .72 ] for no aspirin ; HR , 1.85 [ 95 % CI , 1.22-2 .81 ] ; P = .004 ) .