title: Predictors of the post-thrombotic syndrome during long-term treatment of proximal deep vein thrombosis.
abstract: BACKGROUND
  The post-thrombotic syndrome is a chronic, poorly understood complication of deep venous thrombosis (DVT).
  
  
  OBJECTIVE
  To evaluate predictors of the post-thrombotic syndrome, including intensity of long-term anticoagulation, and to assess the impact of the post-thrombotic syndrome on quality of life.
  
  
  METHODS
  The setting was 13 Canadian hospitals and one US hospital. One hundred and forty-five patients with an unprovoked episode of proximal DVT who were initially treated with 3 months of conventional-intensity warfarin [target International Normalized Ratio (INR) of 2.5] then participated in a trial comparing two intensities of long-term warfarin therapy (target INR 2.5 vs. INR 1.7). Post-thrombotic syndrome was assessed at the end of the trial using a validated clinical scale. Generic and venous disease-specific quality of life was compared in patients with and without the post-thrombotic syndrome. Multivariable regression analyses were performed to identify predictors of the post-thrombotic syndrome and of its severity.
  
  
  RESULTS
  After an average follow-up of 2.2 years, the prevalence of post-thrombotic syndrome was 37% and of severe post-thrombotic syndrome was 4%. Quality of life was worse in patients with the post-thrombotic syndrome compared with patients who did not have it. The presence of factor (F)V Leiden or the prothrombin gene mutation was an independent predictor of both a lower risk (P = 0.006) and reduced severity (P = 0.045) of the post-thrombotic syndrome. Intensity of anticoagulation did not influence the risk of developing the post-thrombotic syndrome.
  
  
  CONCLUSIONS
  The post-thrombotic syndrome is a frequent and burdensome complication of proximal DVT, even among patients maintained on long-term oral anticoagulation. While the presence of FV Leiden or prothrombin gene mutation appears to be associated with a reduced risk of post-thrombotic syndrome, this finding requires further evaluation in prospective studies.
authors.affiliation: McGill University, Montreal, Quebec, Canada. susan.kahn@mcgill.ca
authors.forename: S R
authors.initials: SR
authors.lastname: Kahn
authors.forename: C
authors.initials: C
authors.lastname: Kearon
authors.forename: J A
authors.initials: JA
authors.lastname: Julian
authors.forename: B
authors.initials: B
authors.lastname: Mackinnon
authors.forename: M J
authors.initials: MJ
authors.lastname: Kovacs
authors.forename: P
authors.initials: P
authors.lastname: Wells
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.forename: D R
authors.initials: DR
authors.lastname: Anderson
authors.forename: P
authors.initials: P
authors.lastname: Van Nguyen
authors.forename: C
authors.initials: C
authors.lastname: Demers
authors.forename: S
authors.initials: S
authors.lastname: Solymoss
authors.forename: J
authors.initials: J
authors.lastname: Kassis
authors.forename: W
authors.initials: W
authors.lastname: Geerts
authors.forename: M
authors.initials: M
authors.lastname: Rodger
authors.forename: J
authors.initials: J
authors.lastname: Hambleton
authors.forename: J S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D002170:Canada; D005165:Factor V / Q000235:genetics; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009154:Mutation; D011186:Postphlebitic Syndrome / Q000175:diagnosis*; D015995:Prevalence; D011516:Prothrombin / Q000235:genetics; D011788:Quality of Life; D012306:Risk; D013997:Time Factors; D014481:United States; D020246:Venous Thrombosis / Q000150:complications* / Q000628:therapy*; D014859:Warfarin / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; C095381:factor V Leiden; D014859:Warfarin; D005165:Factor V; D011516:Prothrombin