Duration of treatment with oral anticoagulants for the treatment and prevention of recurrence of deep vein thrombosis and pulmonary embolism

Venous thromboembolism (VTE) occurs when a blood clot is formed in a deep vein or when it detaches itself and lodges in the lung vessels. These clots can be fatal if the blood flow to the heart is blocked. Vitamin K antagonists (VKA) are given to people who have experienced a VTE, to prevent recurrence. The major complication of this treatment is bleeding. The continuing risk of bleeding with drug use and uncertainty regarding the extent of the risk of recurrences makes it important to look at the proper duration of treatment with VKA for these patients. The review authors searched the literature and were able to combine data from eight randomized controlled clinical trials (2994 patients) comparing different durations of treatment with VKA in patients with a symptomatic VTE. Patients on prolonged treatment had a more than five times lower risk of recurrences. On the other hand, they had an almost three times higher risk of bleeding complications. The prolonged use of vitamin K antagonists reduced the risk of recurrent clots as long as they were used but the benefit decreased over time and the risk of major bleeding remained.