Anticoagulation for VTE: Does Extended Duration = Better Outcomes?

How long should anticoagulant therapy be continued in patients with thromboembolic disease?

The challenge in treating venous thromboembolism (VTE) is to prevent recurrent events without significantly increasing the risk of bleeding. What duration of therapy best achieves this goal? Until now, studies have yielded conflicting answers.

Ost and colleagues¹ conducted a meta-analysis of 15 randomized controlled studies that addressed duration of anticoagulation with warfarin or unfractionated heparin in patients with VTE. The researchers found that long-term therapy (median duration of 6 months) resulted in a greater reduction in recurrent thrombotic events than short-term anticoagulation (median duration of 1.75 months). Overall, the incidence of a recurrent event in patients who received long-term therapy was about 21% of the incidence in those who underwent short-term therapy.The reduction in thrombotic events was not accompanied by an increase in bleeding events.

In patients who received longer treatment, the protective effect was maintained after anticoagulation was discontinued; however, it was less pronounced. There were insufficient data in the meta-analysis to determine whether 3 months of anticoagulation is as effective as 6 months.

The older treatment regimens for VTE, in which anticoagulation was discontinued after 4 to 6 weeks, are fraught with an increased risk of recurrent thrombotic events. Longer treatment is indicated, and the optimal duration may be as long as 6 months. Future trials will study regimens that range from 3 to 4 months.