title: Comparison of 3 and 6 months of oral anticoagulant therapy after a first episode of proximal deep vein thrombosis or pulmonary embolism and comparison of 6 and 12 weeks of therapy after isolated calf deep vein thrombosis. Pinede L, Ninet J, Duhaut P et al for the Investigators of the 'Durée Optimale du Traitement Antivitamines K' (DOTAVK) study. Circulation 2001; 103: 2453-60.
abstract: OBJECTIVE
  Is anticoagulant treatment for calf vein thrombosis for 6 weeks duration associated with acceptable recurrence and safety outcomes? Is anticoagulant therapy for 3 months duration for proximal deep vein thrombosis (DVT) or pulmonary embolism (PE) associated with acceptable recurrence and safety outcomes?
  
  
  METHODS
  Men and women with a first episode of symptomatic calf vein thrombosis or proximal DVT confirmed by ultrasound or venography, or PE confirmed by lung scan or angiography. Patients with pregnancy, thrombophilia, severe PE, and cancer were excluded.
  
  
  METHODS
  After treatment with heparin and oral anticoagulants targeting an INR of 2-3, patients with calf DVT were randomized to 6 weeks (n = 105) versus 3 months (n = 92) of treatment, and patients with proximal DVT and/or PE were randomized to 3 months (n = 270) versus 6 months (n = 269) of treatment. The outcome events were recurrences and major, minor, or fatal bleeding complications. The mean follow-up time was 12 months.
  
  
  RESULTS
  A total of 736 patients were enrolled. For calf vein thrombosis the recurrence of DVT or PE after 6 weeks of therapy was 2/105 (2.0%) versus 3/92 (3.4%) with 3 months of therapy, relative risk of 0.58 (95% CI: 0.10-3.36). The rates of major bleeding were 1/105 (1.0%) and 3/92 (3.4%) respectively, relative risk of 0.29 (95% CI: 0.03-2.72). For proximal DVT or PE, the recurrence rate after 3 months of therapy was 21/270 (8.1%) versus 23/269 (8.7%) after 6 months of treatment, relative risk of 0.93 (95% CI: 0.53-1.65). The rates of major bleeding were 5/270 (1.9%) versus 7/269 (2.6%) respectively, relative risk of 0.73 (95% CI: 0.24-2.27).
  
  
  CONCLUSIONS
  After isolated calf vein DVT, 6 weeks of oral anticoagulation is sufficient. For proximal DVT or PE, 3 and 6 months of anticoagulant therapy is equivalent. For patients with temporary risk factors who have a low risk of recurrence, 3 months of treatment seems to be sufficient.
authors.affiliation: Hamilton General Hospital, Ontario, Canada. anands@mcmaster.ca
authors.forename: S S
authors.initials: SS
authors.lastname: Anand
mesh_terms: D000284:Administration, Oral; D000925:Anticoagulants / Q000627:therapeutic use*; D006801:Humans; D011655:Pulmonary Embolism / Q000150:complications* / Q000188:drug therapy*; D013997:Time Factors; D016896:Treatment Outcome; D020246:Venous Thrombosis / Q000150:complications* / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants