d-Dimer Found Useful in Decision to Continue Anticoagulation Following First Idiopathic VTE

Henry I. Bussey, Pharm.D., FCCP, FAHA
December, 2006

Reference: Palareti G, et al. d-Dimer testing to determine the duration of anticoagulation therapy. N Engl J Med 2006; 355:1780-1789.

Patients with an abnormal d-Dimer at one month after completing at least 3 months of anticoagulation for an initial idiopathic VTE were significantly less likely to have a recurrent VTE if their anticoagulation was resumed. Patients without an abnormal d-Dimer did not have their anticoagulation resumed, and their recurrent VTE also was relatively low. Previous studies have found that an elevated d-Dimer at discontinuation of anticoagulation is associated with approximately a two fold increase in the rate of recurrent VTEs, but this is the first study, to my knowledge, that has examined the benefit of resuming anticoagulation in such patients. It should be noted that patients with antiphospholipid antibody and antithrombin deficiency were excluded from this trial. Also, because anticoagulation was stopped for one month before the d-Dimer test was done, it is important to note that 5 of about 600 patients had a recurrent VTE during this initial month following anticoagulation discontinuation. d-Dimer results were not obtained at the time the anticoagulation was discontinued. The overall results of the trial are summarized in the table below.

Thromboembolism and Major Bleeding

^*Occurred after stopping anticoagulation because of repeated falls. Events are by intention-to-treat analysis. All patients had their anticoagulation stopped for one month before entering the trial and 5 VTE events occurred during that month.

Adapted from Palareti et al. N Engl J Med 2006; 355:1780-1789