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 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.