After a first episode of venous thromboembolism

Several advances in the management of venous thromboembolism with anticoagulants have occurred over the past few years. The importance of rapid and adequate treatment with heparin is well established. So is the early introduction of oral warfarin,1 which results in patients being given heparin for shorter periods and having shorter stays in hospitalcompared with days gone by. Nomograms for warfarin have made initial dosing easier and more predictable.2 The widespread use of the international normalised ratio for reporting the effect of warfarin has resulted in more universally accepted recommendations regarding the desirable degree of anticoagulation in given clinical settings. Two aspects of management require further systematic investigation: the correct place to be assigned to low molecular weight heparins and (the topic to be discussed here) the optimal duration of oral anticoagulant treatment after a first symptomatic thromboembolic event. Despite pages covering mechanisms, drug interactions, and other information, instructions regarding the optimal duration of treatment in most textbooks are refreshingly terse and to the point: “Anticoagulation with warfarin is usually continued for 3-6 months.” …