Venous thromboembolism: homocystinaemia increased the risk.

Clinical bottom line (level 3a)

  1. Patients with homocystinaemia were at increased risk of developing venous thromboembolism (NNH = 500 at unknown) .
Ray : Archives of Internal Medicine 1998; 158: 2101-2106
Expires October 2002

The study

Systematic review of all studies of
  • Patients: with homocystinaemia
  • Outcome: venous thromboembolism


    • Articles found in English using MEDLINE, 1980 to 1997 (search terms: homocysteine, homocystine, folate, folic acid and vitamin B12 and thrombophlebitis, deep vein thrombosis, pulmonary embolism and thrombosis ) and searching bibliographies of review articles and letters to editors.

    Selection criteria: see above
    Appraisal criteria: no formal quality grading used
    Articles excluded if:
    • fewer than 10 patients enrolled
    • no measurement of plasma, serum or whole blood homocysteine levels reported
    • no reporting of venous thromboembolism


    9 case-control studies found involving 856 patients
    The studies were not found to be significantly heterogeneous.

    The evidence

    Patient expected event rate for venous thromboembolism: 0.1%
    risk factor for
    venous thromboembolism     		unadjusted OR
    (95% CI)    		 NNH
    (95% CI)
    homocystinaemia 2.95
    (2.08 to 4.17)     		510
    (320 to 930)

    Comments

    1. Limiting the search to English language articles may been important material has been missed.
    2. Many of the studies failed to find appropriate controls, provided limited information about subject recruitment and failed to test for other hypercoagulable mechanisms and other causes of elevated homocysteine levels.
    3. Note that the pooled odds ratio has not been adjusted for confounding factors.

    Citation

    1. Ray JG, : Meta-analysis of hyperhomocysteinemia as a risk factor for venous thromboembolic disease. Archives of Internal Medicine 1998; 158: 2101-2106
    Search Terms: found in 'Other articles noted' section of ACP Journal Club
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer:

    Clinical Question.
    Patient homocystinaemia
    Intervention or Exposure risk factor
    Outcome VTE