Optimal Duration of Anticoagulation After Venous Thromboembolism: Fixed and Evidence-Based, or Flexible and Personalized?

Optimal management of acute venous thromboembolism (VTE) requires institution of rapidly effective and safe anticoagulation. Much clinical investigation has focused on developing convenient and reliable anticoagulation regimens that use parenteral low-molecular-weight heparin or fondaparinux as a “bridge” to oral anticoagulant therapy with warfarin. Many novel oral anticoagulant therapies, administered in fixed doses without routine coagulation monitoring, are in advanced development and have the potential for eventual approval as monotherapy for pulmonary embolism or deep venous thrombosis (DVT).

Although everyone agrees that anticoagulation is the foundation of treatment of VTE, the optimal duration of therapy is hotly debated. Unlike other areas of VTE management, the disagreement is widening, not narrowing. The wording of consensus statements is tentative (couched in vague generalizations) and ambiguous, reflecting the difficulty in finding common ground.

The tension is between a population-based approach and an individualized, personalized strategy. Those favoring a population-based approach treat idiopathic and unprovoked VTE indefinitely, often with lifelong anticoagulation. This category includes patients who develop VTE during long-haul air travel, as well as others whose VTE occurs “out of the blue.” It accounts for about half of the cases of VTE. In this treatment approach, the clinical scenario drives the duration of VTE treatment. In other words, patients with unprovoked VTE receive lifelong anticoagulation. Period.

In this population-based approach, patients with secondary or provoked VTE receive anticoagulation for a fixed duration. In the United States, these patients are usually treated for 3 months for isolated calf vein thrombosis or upper-extremity thrombosis and 6 months for proximal leg or pelvic DVT and for pulmonary embolism of any size. By definition, secondary VTE occurs after trauma, surgery, use of birth control pills, pregnancy, or hormone replacement therapy. Venous thromboembolism in the setting of cancer is a special case: By consensus, treatment continues until the cancer …