Twelve RCTs (n=6,310, range 52 to 2,206) were included in the review. One included study was not truly randomised (patients were allocated based on odd or even year of birth).
Compared with control (four trials, n=530), oral anticoagulation showed a statistically nonsignificant trend toward reduction in combined death, recurrent ischaemic stroke and myocardial infarction (OR 0.73, 95% CI 0.39 to 1.36, p=0.073), ischaemic stroke (p=0.13) and TIA (p=0.14). Total bleeds (OR 12.72, 95% CI 2.18 to 74.15), major bleeds (OR 6.42, 95% CI 2.02 to 20.41) and haemorrhagic strokes (OR 4.90, 95% CI 1.33 to 18.11) were all significantly greater in the oral anticoagulation group. There was no impact on all-cause mortality.
Compared with antiplatelet therapy, moderate-intensity oral anticoagulation (international normalised ratio 2.1 to 3.6; eight trials, n=4,464), showed no statistically significant difference in combined death, recurrent ischaemic stroke and myocardial infarction (p=0.93), recurrent ischaemic stroke (p=0.71) and all-cause mortality (p=0.18). Total bleeds (OR 2.18, 95% CI 1.39 to 3.41) and major bleeds (OR 2.03, 95% CI 1.49 to 2.76) were significantly greater in the oral anticoagulation group.
One trial (n=1,316) that evaluated high-intensity oral anticoagulation (international normalised ratio 3.0 to 4.5) against antiplatelet therapy stopped early because of an excess of haemorrhagic stroke in the oral anticoagulation arm (OR 8.45, 95% CI 2.53 to 28.19). Major bleeds were significantly greater in the oral anticoagulation group (OR 10.29, 95% CI 3.12 to 33.94).