Anticoagulation after venous thromboembolism. Deciding on the optimal duration.

Deciding on the optimal duration of anticoagulation is based on the risk of recurrent venous thromboembolism (VTE) and of bleeding during anticoagulation. The duration of anticoagulation should be at least three months since shorter courses double the recurrence rates. At three months anticoagulation can be stopped in patients with a VTE provoked by a transient risk factor, as the recurrence risk is expected to be lower than the bleeding risk during anticoagulation. Patients with unprovoked VTE are at higher risk of recurrence and prolonged anticoagulation is currently recommended. However, attempts are made to stratify these patients according to their recurrence risk and to identify those with a low recurrence risk who would not benefit from extended anticoagulation. Novel approaches to optimize the management of patients with unprovoked VTE are the use of prediction models which link clinical patient characteristics with laboratory testing to discriminate between patients with a low risk (who may discontinue anticoagulation) and those with high risk (in whom long term anticoagulation is justified). Moreover, new antithrombotic concepts including new oral anticoagulants or aspirin both of which potentially confer a lower bleeding risk and are more convenient for the patients have been explored for extended thromboprophylaxis.