Duration of anticoagulant therapy for venous thromboembolism

The risk of bleeding, as well as patient preferences, must be considered when deciding duration of warfarin therapy

Venous thromboembolism (VTE) affects about 17 000 Australians each year, usually as deep vein thrombosis (DVT) of the legs or pulmonary embolism (PE).1 The sequelae of VTE include death, post-thrombotic syndrome, chronic pulmonary thromboembolic disease and recurrent VTE. Anticoagulation with an oral vitamin K antagonist (warfarin), overlapped for the first 5–7 days with unfractionated heparin, low-molecular-weight heparin or fondaparinux, prevents thrombus progression and reduces the risk of recurrent VTE and death during the acute phase.2,3 When treatment is continued beyond the acute phase, warfarin reduces the risk of recurrent VTE but increases the risk of bleeding and requires frequent laboratory monitoring, which is inconvenient for patients. Thus, decisions regarding the optimal duration of anticoagulant therapy must balance the increased risk and sequelae of recurrent VTE when warfarin is stopped against the risk of bleeding and the inconvenience of continuing treatment.3