title: Does the location of thrombosis determine the risk of disease recurrence in patients with proximal deep vein thrombosis?
abstract: OBJECTIVE
  To determine if the location of deep vein thrombosis is a predictor of recurrent venous thromboembolism during the initial 3 months of anticoagulant therapy.
  
  
  METHODS
  The study population consisted of 1,149 consecutive patients with symptomatic proximal deep vein thrombosis. In all patients, deep vein thrombosis was confirmed by Duplex ultrasound or venography and was classified as popliteal, femoral, or iliofemoral. Patients received initial treatment with unfractionated heparin, enoxaparin, or reviparin for least 4 days, as well as a coumarin derivative, with a target international normalized ratio of 2.0 to 3.0, starting on the 1st or 2nd day of treatment. All patients were followed for 3 months, and all episodes of recurrent venous thromboembolism were confirmed with objective diagnostic tests.
  
  
  RESULTS
  The overall rate of recurrent venous thromboembolism during the initial 3 months of anticoagulant therapy was 5.5% (63/1,149). The rate of recurrence in patients with popliteal vein thrombosis was 5.1% (23/453); in patients with femoral vein thrombosis, it was 5.3% (34/645); and in patients with iliofemoral vein thrombosis, it was 11.8% (6/51). Two clinical risk factors were associated with an increased risk of recurrent venous thromboembolism: iliofemoral vein thrombosis (odds ratio [OR] = 2.4; 95% confidence interval [CI]: 0.95, 5.9), and cancer (OR = 2.6; 95% CI: 1.5, 4.4).
  
  
  CONCLUSIONS
  Patients with extensive iliofemoral vein thrombosis who receive conventional anticoagulant therapy have a greater than twofold higher risk of developing recurrent venous thromboembolism than patients without iliac vein involvement (i.e., 11.8% vs. 5.2%). Prospective studies are needed to determine whether alternative antithrombotic strategies are warranted in such patients.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada. jdouket@fhs.mcmaster.ca
authors.forename: J D
authors.initials: JD
authors.lastname: Douketis
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.forename: G A
authors.initials: GA
authors.lastname: Foster
authors.forename: J S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D005260:Female; D005268:Femoral Vein; D006801:Humans; D008297:Male; D008875:Middle Aged; D010690:Phlebography; D011152:Popliteal Vein; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D012044:Regression Analysis; D012307:Risk Factors; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000145:classification / Q000000981:diagnostic imaging / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants