A Cochrane meta-analysis of 8 RCTs, totaling 2994 patients, evaluated duration of treatment with vitamin K antagonists in DVT. It concluded that although prolonged treatment with vitamin K antagonists reduces the risk of DVT, substantial ongoing risk of bleeding complications remains.9 Prolonged or even lifelong treatment may be considered for high-risk patients with multiple episodes of DVT or pulmonary embolism.
Cost-effectiveness analysis suggests that prolonged warfarin therapy for patients with the highest risk thrombophilic conditions (homozygous factor V Leiden and antiphospholipid antibody syndrome) also may be warranted.8
Recommendations
A consensus opinion from the British Society for Haematology concludes that:
- thrombophilia testing of unselected patients is inappropriate
- initial management of DVT or pulmonary embolism in patients with heritable thrombophilia is no different from that in other patients
- identification of the most prevalent forms of heritable thrombophilia, heterozygous factor V Leiden or prothrombin G20210A, shouldn’t influence decisions about duration of anticoagulation therapy.10
The consensus statement suggests indefinite anticoagulation for patients with 2 or more spontaneous venous thrombotic events.