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Long-Term, Low-Intensity Warfarin Prevents Recurrence of Venous Thromboembolism
Patients with idiopathic venous thromboembolism who had received full-dose anticoagulation therapy for a median of 6.5 months were randomly assigned to placebo or low-intensity warfarin.
The trial was terminated early after 508 patients had undergone randomization and had been followed for up to 4.3 years. Of 253 patients assigned to placebo, 37 had recurrent venous thromboembolism, as compared with 14 of 255 patients assigned to low-intensity warfarin, a risk reduction of 64 percent. Risk reductions were similar for all subgroups, including those with and those without inherited thrombophilia.
The standard therapy to treat recurrent venous thromboembolism involves three to 12 months of treatment with full-dose warfarin with a target international normalized ratio (INR) between 2.0 and 3.0. However, for long-term management, no therapeutic agent has shown an acceptable benefit-to-risk ratio.
Major hemorrhage occurred in two patients assigned to placebo and five assigned to low-intensity warfarin. Eight patients in the placebo group and four in the group assigned to low-intensity warfarin died.
Patients given low-intensity warfarin exhibited a 48 percent reduction in the composite end point of recurrent venous thromboembolism, major hemorrhage, or death. According to per-protocol and as-treated analyses, the reduction in the risk of recurrent venous thromboembolism was between 76 and 81 percent.
The researchers concluded that long-term, low-intensity warfarin therapy is a highly effective method of preventing recurrent venous thromboembolism.
The abstract is available by clicking here: NEJM Web site.