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D-Dimer to Determine Duration of Anticoagulation After Venous Thromboembolism

A normal D-dimer level at 1 month after anticoagulation is discontinued predicts a low risk for recurrence, even if anticoagulation is not reinstated.

High D-dimer levels, measured after anticoagulation is discontinued in patients with venous thromboembolism (VTE), are associated with increased risk for recurrent VTE (Journal Watch Sep 9 2003). Thus, we can logically ask whether D-dimer levels can guide decisions about duration of anticoagulation.

Italian researchers enrolled 608 patients who received oral anticoagulation after a first unprovoked deep-vein thrombosis or pulmonary embolism; patients with provoking factors (e.g., fracture, immobilization, surgery, cancer, antiphospholipid antibodies, or antithrombin deficiency) were excluded. Anticoagulation was stopped after 3 months, and qualitative D-dimer testing was performed a month later. The 385 patients with normal D-dimer levels did not resume anticoagulation. The remaining 223 patients were randomized to either resume or not resume anticoagulation. During a mean follow-up of 1.4 years, the incidence of the primary endpoint (recurrent VTE or major bleeding episode) was significantly higher among patients with high D-dimer levels who did not resume anticoagulation (15%; all VTEs) than among those who did resume anticoagulation (3%; 2 VTEs and 1 major bleed). Among patients with normal D-dimer levels, the endpoint occurred in 6% (all VTEs).

Comment: This study suggests that a high D-dimer level, measured after 3 months of anticoagulation in patients with unprovoked venous thromboembolism, should push us in the direction of continuing anticoagulation (although the optimal duration of anticoagulation for these patients is uncertain). However, even among patients with normal D-dimer levels, the rate of recurrent VTE was 6%, so the optimal approach to this group remains unclear.

— Allan S. Brett, MD

Published in Journal Watch General Medicine October 31, 2006

Citation(s):

Palareti G et al. D-dimer testing to determine the duration of anticoagulation therapy. N Engl J Med 2006 Oct 26; 355:1780-9.

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