Anticoagulant prophylaxis to prevent asymptomatic deep vein thrombosis in hospitalized medical patients: a systematic review and meta-analysis

J Thromb Haemost. 2008 Mar;6(3):405-14. doi: 10.1111/j.1538-7836.2007.02847.x. Epub 2007 Nov 20.


Background: The effect of anticoagulant prophylaxis on the prevention of deep vein thrombosis (DVT) should include an investigation of both clinical and subclinical DVT. We conducted a systematic review to determine whether anticoagulant prophylaxis reduces the risk of asymptomatic DVT compared to no prophylaxis in at-risk hospitalized medical patients.

Methods: MEDLINE, EMBASE, and the Cochrane Library were searched through March 2007 for randomized trials of anticoagulant prophylaxis for the prevention of asymptomatic DVT, assessed by venogram or ultrasound. We assessed four outcomes: all asymptomatic DVT, asymptomatic proximal DVT, major bleeding and mortality. Random effects meta-analyses were performed and results were expressed using relative risk (RR) and 95% confidence intervals (95% CIs).

Results: Four trials including 5516 patients were eligible. Our pooled analysis demonstrated that compared to placebo, anticoagulant prophylaxis was associated with a significantly lower risk of any asymptomatic DVT (RR 0.51; 95% CI 0.39-0.67) and asymptomatic proximal DVT (RR 0.45; 95% CI 0.31-0.65). Anticoagulant prophylaxis was associated with a significantly increased risk of major bleeding compared to placebo (RR 2.00; 95% CI 1.05-3.79). There was no significant difference in the pooled estimate for all-cause mortality. Anticoagulant prophylaxis conferred an absolute risk reduction of any DVT and proximal DVT of 2.6% and 1.8%, respectively, and was associated with a 0.5% absolute risk increase in major bleeding.

Conclusions: Anticoagulant prophylaxis is effective in preventing asymptomatic DVT in at-risk hospitalized medical patients but is associated with an increased bleeding risk. The therapeutic benefits of anticoagulant prophylaxis appear to outweigh the risks of bleeding.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Anticoagulants / pharmacology*
  • Hemorrhage
  • Heparin, Low-Molecular-Weight / therapeutic use
  • Hospitalization
  • Humans
  • Placebos
  • Randomized Controlled Trials as Topic
  • Risk
  • Treatment Outcome
  • Venous Thrombosis / drug therapy*
  • Venous Thrombosis / prevention & control*


  • Anticoagulants
  • Heparin, Low-Molecular-Weight
  • Placebos