Twelve RCTs were included in the review (3,766 participants, range 25 to 1,360). Ten trials were awarded A for true randomisation and concealed allocation. Six trials were reported as double-blind. Eight trials used intention-to-treat analyses. Loss to follow-up ranged from zero to 65.8%.
There was a significant reduction in stroke recurrence for dual antiplatelet therapy compared with mono antiplatelet therapy regardless of the drugs used (RR 0.67, 95% CI 0.49 to 0.93; 11 trials). There was no evidence of heterogeneity in this analysis (Ι²=0%). Using a funnel plot and the Egger test, the authors reported that there was no evidence of publication bias.
Dual antiplatelet therapy was associated with a significant reduction of composite vascular events (stroke, myocardial infarction, vascular death) (RR 0.75, 95% CI 0.56 to 0.99; 10 trials) and combined stroke, transient ischaemic attack and all death (RR 0.71, 95% CI 0.56 to 0.91; eight trials). No heterogeneity was found in any of these analyses. Findings of assessments of publication bias were not reported for these analyses.
Findings on major bleeding, poor functional outcome, fatal stroke, transient ischaemic attack, myocardial infarction, intracerebral haemorrhage, death and vascular death were non significant and there was no evidence of heterogeneity.