Optimal duration of anticoagulant therapy after an episode of venous thromboembolism.

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism (VTE) is still a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. The aims of this paper are to describe the current concepts in this field. Recent data, based on randomized controlled trials, suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of VTE and the presence of risk factors. A 6-week treatment for patients with isolated calf vein thrombosis is sufficient. For proximal thrombosis and/or pulmonary embolism, a short anticoagulant course is sufficient in patients with temporary risk factors (3 months), and a longer anticoagulant course (6 months at least) is recommended for cases with permanent risk factors or idiopathic VTE. For these high-risk of recurrence patients, an assessment of low- or fixed-dose oral anticoagulation is necessary in order to reduce the bleeding risk. It is not possible to precisely determine the optimal duration with the available data. We have already performed a meta-analysis on summary data that suggests a long course of oral anticoagulant therapy is superior to a short course. An individual meta-analytic approach is needed to draw more precise conclusions on an interesting and important clinical topic.