Venous thromboembolism: long-term LMWH causes less minor bleeding than warfarin

Clinical bottom line (level 2a)

  1. Patients with venous thromboembolism who receive long-term LMWH compared with warfarin have less minor bleeding.
  2. There is no clear difference in recurrent venous thromboembolism or major bleeding between the two groups.
Marchetti et al: Am J Med 2001; 111 : 130-139
Expires May 2004

The study

Systematic review of all longitudinal studies of
  • Patients: venous thromboembolism
  • Intervention: long-term LMWH compared with warfarin
  • Outcome: bleeding, recurrent venous thromboembolism

Articles found in English only using Medline, 1966 to December 2000 (search terms: heparin, low-molecular weight, and coumarins or warfarin and follow-up studies or recurrence in MeSH ) and searching journals dealing with thrombosis after 1990

Selection criteria: see above and below
Appraisal criteria: not given
Articles excluded if:
  • follow-up < 3 months
  • no objective assessment of venous thromboembolism or bleeding
5 RCTs and 1 prospective cohort study found involving 1184 patients
Study outcomes were not found to be significantly heterogeneous.

The evidence

Outcome Time to outcome CER OR
(95% CI)		 NNT
(95% CI)
deep vein thrombosis 3 months /
(%)		 0.77
(0.43 to 1.35)
pulmonary embolism 3 months /
(%)		 0.60
(0.24 to 1.49)
major bleeding 3 months 52/617
(8.4%)		 0.73
(0.28 to 1.91) 		47
(NNT = 17 to infinity;
NNH = 15 to infinity)
minor bleeding 3 months /
(%)		 0.28
(0.16 to 0.48)

Comments

  1. Control rates were generally not given so NNTs could not be calculated.

Citation

  1. Marchetti M, Pistorio A, Barone M, et al: low-molecular-weight heparin versus warfarin for secondary prophylaxis of venous thromboembolism: a cost-effectiveness analysis. Am J Med 2001; 111 : 130-139
Search Terms: from ACP Journal Club other articles noted
Contributor: Chris Ball, May 2002
Reviewer:

Clinical Question.
Patient venous thromboembolism
Intervention or Exposure long-term LMWH
Comparison warfarin
Outcome recurrent venous thromboembolism, bleeding