Duration of anticoagulation for venous thromboembolism.

The duration of oral anticoagulant therapy for venous thromboembolism (VTE) depends on the risk of recurrence if treatment is stopped and the risk of bleeding if treatment is continued. If the risk of recurrence is low (e.g., thrombosis provoked by a major reversible risk factor such as surgery), 3 months of treatment is usually adequate. If the risk of recurrence is high (unprovoked "idiopathic" VTE or associated with a non-reversible risk factor such as active cancer), 6 months or indefinite anticoagulant therapy is indicated. The presence of malignancy, an antiphospholipid antibody, and other selected thrombophilic states suggests more prolonged therapy, whereas isolated distal deep vein thrombosis, high risk of bleeding, and patient preference suggest a shorter course of treatment.