Deep vein thrombosis: LMWH decreases recurrence.

Clinical bottom line (level 1a)

  1. Patients with a first venous thromboembolism who are given low-molecular-weight-heparin are less likely to have a recurrence than those given unfractionated heparin (NNT = 27 at 90 days) .
  2. About twice as many patients given unfractionated heparin have a bleed.
Siragusa et al: New England Journal of Medicine 1996; 100: 269-277
Expires December 2003

The study

Systematic review of randomised controlled trials of
  • Patients: first episode of acute deep vein thrombosis objectively confirmed by venography or acute pulmonary embolism confirmed by high-probability lung scan or pulmonary angiography
  • Intervention: low molecular weight heparin compared with unfractionated heparin
  • Outcome: recurrent thromboembolism, bleeding, death


    • Articles found in all using MEDLINE, EMBASE, 1980-1994 (search terms: low-molecular-weight-heparin, enoxaparin, Logiparin, CY 222, Fraxiparine and fragmin, associated with the terms treatment, thromboembolic disease, deep vein thrombosis and pulmonary embolism ) and scanning reference lists and contacting authors of all retrieved articles

    Selection criteria: as above
    Appraisal criteria: detailed in text
    Articles excluded if: not first episode or no objective confirmation of diagnosis

    13 studies were included. 3 studies were deemed to be 'level 1', ie. had blinded outcomes. If it was unclear whether the outcomes were blinded (or they were unblinded) they graded level 2.
    Heterogeneity was not mentioned.

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    recurrent VTE in level 1 studies 15 days
    (3.2%)
    (0.8%)    		 76%
    (20% to 94%)    		 2.4%
    (% to %)    		 41
    (21 to 234)
    recurrent VTE in level 1 studies 90 days
    (6.4%)
    (2.7%)    		 61%
    (20% to 70%)    		 3.7%
    (% to %)    		 27
    (14 to 136)

    • Major bleeding in level 1 studies:
      • unfractionated heparin: 6.7%
      • LMWH: 3.0%
    • In level 2 studies, no significant differences were found in recurrence or major bleeding.

    Comments

    1. This CAT was written from the ACP Journal Club summary of the original paper, and data was taken from their calculations. It was confirmed by analysis of the original article.

    Citation

    1. Siragusa S, Cosni B, Piovella F, et al: Meta-analysis: LMWH is effective in reducing recurrent thromboembolism, bleeding, and death in acute DVT. New England Journal of Medicine 1996; 100: 269-277
    Contributor: Clare Wotton and Bob Phillips, December 2000
    Reviewer:

    Clinical Question.
    Patient DVT
    Intervention or Exposure LMWH
    Comparison unfractionated heparin
    Outcome recurrent thromboembolism, bleeding, death