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Dabigatran “non-inferior” to warfarin, but only just

BMJ 2013; 346 doi: (Published 27 February 2013) Cite this as: BMJ 2013;346:f1219

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New oral anticoagulants offer the prospect of stability and convenience for people needing treatment for a recent deep vein thrombosis or pulmonary embolus. They might also allow longer term treatment to prevent recurrence, and Boehringer Ingelheim recently reported results from a pair of trials that tested extended use of their new agent dabigatran, a direct thrombin inhibitor. Dabigatran looked non-inferior to warfarin in a head to head trial (risk of recurrence 1.8% (26/1430) v 1.3% (18/1426); hazard ratio 1.44, 95% CI 0.78 to 2.64) and caused significantly fewer bleeds of any severity (19.4% v 26.2%; 0.71, 0.61 to 0.83). All participants had completed treatment for a first unprovoked episode of venous thromboembolism and were judged to be at risk of a second. They took warfarin or dabigatran for an extra six to 36 months. Dabigatran worked better than a placebo in a smaller sister trial and caused more bleeding.

The authors admit they were generous with their non-inferiority margin in the head to head comparison, which allowed a risk increase of nearly threefold (2.85) to be accepted as non-inferior. The upper confidence limit around the main results came close, and the editorial says doubts remain about this and other new oral anticoagulants (p 767). Dabigatran was associated with a significantly higher risk than warfarin of acute coronary syndrome (0.9% v 0.2%; P=0.02). Others have reported similar concerns and the association deserves further scrutiny, says the editorial.


Cite this as: BMJ 2013;346:f1219

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