How long to anticoagulate?

Abstract

Anticoagulant drugs have dramatically decreased the morbidity and mortality associated with venous thromboembolism (VTE). Although early antithrombotic treatment is straightforward, doubts still exist in the decision process of ‘how long to anticoagulate?’ It is common practice among physicians to stop anticoagulation in those who had one episode of VTE; deep vein thrombosis or pulmonary embolism (PE), after 3–6 months and recommend long-term anticoagulation in those who had a second event. Recent studies have however identified risk stratification models which could help in determining the duration of anticoagulation. The decision on the duration of anticoagulant treatment should be based on the balance between benefits of preventing a recurrent VTE episode and the risks of bleeding from the drugs. The first step in this regard is to identify if there has been a precipitating factor for the VTE. These commonly are surgery, periods of immobilization like after needing a plaster cast and hormonal treatments like oral contraceptive pill. In these patients, the risk of VTE recurrence is ∼5% in the first year after stopping anticoagulant therapy. The latest American College of Chest Physicians guidance on VTE management consider this risk to be low enough to discontinue anticoagulant therapy at the end of 3 months.1,2 The only practical point in this scenario is how confidently the precipitating factor can be linked to the VTE event. For example, if the thrombotic episode occurred more than 3 months after the surgery, can this be considered as a provoked event? If the female develops a PE after being on the …