D-dimer to Establish Duration of Anticoagulation After Venous Thromboembolism

D-dimer Test to Establish Duration of Anticoagulation After a First Idiopathic Episode of Venous Thromboembolism; the Prospective Randomized "Prolong" Study

The optimal duration of oral anticoagulant treatment in patients with idiopathic venous thromboembolism is still uncertain. The present study addresses the possible role of the D-dimer test in assessing the need for continuation of anticoagulation.The study aims at assessing whether D-dimer assay may have a role in guiding the duration of anticoagulation in these patients

This is a multicenter prospective follow-up study in patients with a first episode of symptomatic idiopathic venous thromboembolism (proximal deep vein thrombosis and/or pulmonary embolism) who are treated with vitamin K antagonists (either warfarin or acenocoumarol) for a minimum of 3 months. Eligible patients who give informed consent are instructed to immediately stop oral anticoagulation and refrain from taking any other antithrombotic drugs until the next visit, scheduled after 30 days. At that visit, venous blood is sampled to perform D-dimer assay and thrombophilia tests. D-dimers are assessed using the Clearview Simplify D-dimer assay (Agen Biomedical Limited, Brisbane, Australia). Patients with normal D-dimer results do not continue anticoagulation, whereas those with elevated D-dimer results are randomized using a computer program to either stop or resume anticoagulation with vitamin K antagonists (INR 2.0-3.0). All patients are followed-up for 18 months. The study outcome are the composite of confirmed recurrent venous thromboembolism and major bleeding events. All suspected outcome events and all deaths are evaluated by a central adjudication committee whose members are unaware of the D-dimer and thrombophilia results and of the group assignments.

Inclusion Criteria:

• Age > 18 years
• After a first documented idiopathic proximal deep vein thrombosis and/or pulmonary embolism
• After at least 3 months of oral anticoagulation
• After written informed consent

Exclusion Criteria:

• If the Venous thromboembolism occurred:
• during pregnancy or puerperium
• after recent (i.e. within three months) fracture or plaster casting of a leg,
• after immobilization with confinement to bed for three consecutive days
• after surgery with general anesthesia lasting longer than 30 minutes
• Patients with:
• active cancer
• antiphospholipid antibody syndrome
• antithrombin deficiency
• serious liver disease or renal insufficiency (creatininemia > 2 mg/dL),
• other indications for anticoagulation or contraindications for this treatment
• limited life expectation
• Patients who live too far from the clinical center