title: Homocysteine-lowering therapy and risk for venous thromboembolism: a randomized trial.
abstract: BACKGROUND
  Elevated total homocysteine levels are associated with a higher risk for venous thromboembolism. Whether decreasing homocysteine levels with vitamin therapy reduces the risk for venous thromboembolism is not known.
  
  
  OBJECTIVE
  To determine whether decreasing homocysteine levels alters the risk for symptomatic venous thromboembolism.
  
  
  METHODS
  Secondary analysis of data from the randomized, placebo-controlled Heart Outcomes Prevention Evaluation 2 (HOPE-2) trial.
  
  
  METHODS
  145 clinical centers in 13 countries.
  
  
  METHODS
  5522 persons 55 years of age or older with known cardiovascular disease or diabetes mellitus and at least 1 other risk factor for vascular disease.
  
  
  METHODS
  A daily supplement of 2.5 mg of folic acid, 50 mg of vitamin B(6), and 1 mg of vitamin B(12) or matching placebo for 5 years.
  
  
  METHODS
  Prospectively diagnosed and confirmed symptomatic deep venous thrombosis or pulmonary embolism.
  
  
  RESULTS
  The geometric mean homocysteine level decreased by 2.2 micromol/L in the vitamin therapy group and increased by 0.80 micromol/L in the placebo group. Venous thromboembolism occurred in 88 participants during a mean follow-up of 5 years. The incidence rate of venous thromboembolism was the same in the vitamin therapy group and the placebo group (0.35 per 100 person-years; hazard ratio, 1.01 [95% CI, 0.66 to 1.53]). Vitamin therapy did not reduce the risk for deep venous thrombosis (hazard ratio, 1.04 [CI, 0.63 to 1.72]), pulmonary embolism (hazard ratio, 1.14 [CI, 0.57 to 2.28]), or unprovoked venous thromboembolism (hazard ratio, 1.21 [CI, 0.66 to 2.23]).
  
  
  CONCLUSIONS
  The proportion of patients with a previous episode of venous thromboembolism at enrollment was not known, and venous thromboembolism events were not centrally adjudicated.
  
  
  CONCLUSIONS
  Decreasing homocysteine levels with folic acid and vitamins B6 and B12 did not reduce the risk for symptomatic venous thromboembolism.
authors.affiliation: Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. rayj@smh.toronto.on.ca
authors.forename: Joel G
authors.initials: JG
authors.lastname: Ray
authors.forename: Clive
authors.initials: C
authors.lastname: Kearon
authors.forename: Qilong
authors.initials: Q
authors.lastname: Yi
authors.forename: Patrick
authors.initials: P
authors.lastname: Sheridan
authors.forename: Eva
authors.initials: E
authors.lastname: Lonn
mesh_terms: D000368:Aged; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000188:drug therapy*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000517:prevention & control*; D012307:Risk Factors; D013923:Thromboembolism; D020246:Venous Thrombosis / Q000453:epidemiology / Q000517:prevention & control*; D014805:Vitamin B 12 / Q000627:therapeutic use*; D025101:Vitamin B 6 / Q000627:therapeutic use*
chemical_list: D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12