It is common practice to treat acute proximal vein thrombosis with an initial course of heparin and to follow this with oral anticoagulant therapy for a period of weeks to months to prevent delayed recurrence of venous thromboembolism. Until recently, the evidence that oral anticoagulant therapy should be used for this purpose was limited to one retrospective study1 in which the frequency of clinically diagnosed recurrence was reported to be lower in patients who were treated with oral anticoagulants on a long-term basis than in a group who received no long-term therapy.
The development, during the last decade, of objective noninvasive diagnostic tests for venous thrombosis together with the application of rigorous methodology in the design of clinical trials has made it possible to reevaluate the need for long-term treatment of venous thrombosis. To do this, we performed three randomized clinical trials, the results of which have provided practical
Hull R, Hirsh J. Long-term Anticoagulant Therapy in Patients With Venous Thrombosis. Arch Intern Med. 1983;143(11):2061–2063. doi:10.1001/archinte.1983.00350110039009