Aspirin Found To Prevent Recurrent Venous Thromboembolism

Aspirin can help prevent the recurrence of venous thromboembolism (VTE) after discontinuation of anticoagulation therapy, according to results of the WARFASA (the Warfarin and Aspirin) study published in the New England Journal of Medicine.

Following 6 to 18 months of oral anticoagulation, 403 patients with first-time unprovoked VTE were randomized to aspirin (100 mg daily) or placebo for two years. Aspirin therapy resulted in a significant reduction in VTE but did not cause an increase in the risk of bleeding:

  • VTE recurrence: 6.6% per year in the aspirin group versus 11.2% in the placebo group (hazard ratio 0.58, CI 0.36 to 0.93, p=0.02).
  • Major bleeding occurred in one patient in each treatment group.

In an accompanying editorial, Richard Becker writes that the results of WARFASA “are compelling and may signal an important step in the evolution of care” but calls for additional studies to more precisely define the role of aspirin in preventing recurrent VTE. The results of a larger trial, the Aspirin to Prevent Recurrent Venous Thromboembolism (ASPIRE) study, will be reported this year, according to Becker, and, in conjunction with WARFASA, “may provide more reliable evidence of the effect of aspirin in patients with first unprovoked venous thromboembolism.”


  1. dearieme says:

    Bleeding: 1 vs 1 – really, to be usefully confident you’d want a much larger trial.

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