Nonvitamin-K-Antagonist Oral Anticoagulants in Patients With Atrial Fibrillation and Previous Stroke or Transient Ischemic Attack: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

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Abstract

Background and Purpose—

To assess whether the combined analysis of all phase III trials of nonvitamin-K-antagonist (non-VKA) oral anticoagulants in patients with atrial fibrillation and previous stroke or transient ischemic attack shows a significant difference in efficacy or safety compared with warfarin.

Methods—

We searched PubMed until May 31, 2012, for randomized clinical trials using the following search items: atrial fibrillation, anticoagulation, warfarin, and previous stroke or transient ischemic attack. Studies had to be phase III trials in atrial fibrillation patients comparing warfarin with a non-VKA currently on the market or with the intention to be brought to the market in North America or Europe. Analysis was performed on intention-to-treat basis. A fixed-effects model was used as more appropriate than a random-effects model when combining a small number of studies.

Results—

Among 47 potentially eligible articles, 3 were included in the meta-analysis. In 14 527 patients, non-VKAs were associated with a significant reduction of stroke/systemic embolism (odds ratios, 0.85 [95% CI, 074–0.99]; relative risk reduction, 14%; absolute risk reduction, 0.7%; number needed to treat, 134 over 1.8–2.0 years) compared with warfarin. Non-VKAs were also associated with a significant reduction of major bleeding compared with warfarin (odds ratios, 0.86 [95% CI, 075–0.99]; relative risk reduction, 13%; absolute risk reduction, 0.8%; number needed to treat, 125), mainly driven by the significant reduction of hemorrhagic stroke (odds ratios, 0.44 [95% CI, 032–0.62]; relative risk reduction, 57.9%; absolute risk reduction, 0.7%; number needed to treat, 139).

Conclusions—

In the context of the significant limitations of combining the results of disparate trials of different agents, non-VKAs seem to be associated with a significant reduction in rates of stroke or systemic embolism, hemorrhagic stroke, and major bleeding when compared with warfarin in patients with previous stroke or transient ischemic attack.

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