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Secondary prevention of venous thromboembolism

BMJ 2013; 347 doi: (Published 09 September 2013) Cite this as: BMJ 2013;347:f5440
  1. Sam Schulman, professor of medicine12,
  2. James Douketis, professor of medicine2
  1. 1Thrombosis Service, HHS-General Hospital, Hamilton, ON, Canada L8L 2X2
  2. 2Department of Medicine and Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Canada
  1. schulms{at}

Emerging anticoagulation treatments not more effective but safer than warfarin

The seemingly endless debate on the optimal duration of anticoagulation after unprovoked venous thromboembolism has been accorded another dimension. With the addition of new oral anticoagulants (NOACs) and aspirin being evaluated for extended duration prophylaxis after three to six months of anticoagulant therapy for venous thromboembolism, there are now alternatives to treatment with vitamin K antagonists. But this has come at the cost of increased uncertainty among physicians who are less familiar with the recent trials of different agents and the interpretation of these results. Adding to the murkiness is the paucity of head to head comparisons between the NOACs and comparisons of each compound to vitamin K antagonists, administered to achieve an international normalised ratio (INR) of 2.0 to 3.0, which has been the reference standard. So far, only one such trial has been performed—dabigatran versus warfarin.1 To clarify the relative benefits and harms of emerging treatments for extended prophylaxis against disease recurrence in patients with unprovoked venous thromboembolism, Castellucci and colleagues (doi:10.1136/bmj.f5133) present a network meta-analysis of 13 randomised trials, totalling 12 000 patients.2

Studies in atrial fibrillation have shown that NOACs are at least as efficacious (dabigatran 110 mg twice daily, rivaroxaban 20 mg daily, apixaban 5 mg twice daily)3 4 5 or more efficacious (dabigatran 150 mg twice daily) as warfarin for ischaemic stroke prevention.3 However, warfarin remains the best treatment for …

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