Meta-analysis: Anticoagulant Prophylaxis to Prevent Symptomatic Venous Thromboembolism in Hospitalized Medical Patients

20 February 2007 | Volume 146 Issue 4 | Pages 278-288

Background: Underutilization of anticoagulant prophylaxis may be due to lack of evidence that prophylaxis prevents clinically important outcomes in hospitalized medical patients at risk for venous thromboembolism.

Purpose: To assess the effects of anticoagulant prophylaxis in reducing clinically important outcomes in hospitalized medical patients.

Data Sources: MEDLINE, EMBASE, and Cochrane databases were searched to September 2006 without language restrictions.

Study Selection: Randomized trials comparing anticoagulant prophylaxis with no treatment in hospitalized medical patients.

Data Extraction: Any symptomatic pulmonary embolism (PE), fatal PE, symptomatic deep venous thrombosis, all-cause mortality, and major bleeding. Pooled relative risks and associated 95% CIs were calculated. For treatment effects that were statistically significant, the authors determined the absolute risk reduction and the number needed to treat for benefit (NNT_B) to prevent an outcome.

Data Synthesis: 9 studies (n = 19 958) were included. During anticoagulant prophylaxis, patients had significant reductions in any PE (relative risk, 0.43 [CI, 0.26 to 0.71]; absolute risk reduction, 0.29%; NNT_B, 345) and fatal PE (relative risk, 0.38 [CI, 0.21 to 0.69]; absolute risk reduction, 0.25%; NNT_B, 400), a nonsignificant reduction in symptomatic deep venous thrombosis (relative risk, 0.47 [CI, 0.22 to 1.00]), and a nonsignificant increase in major bleeding (relative risk, 1.32 [CI, 0.73 to 2.37]). Anticoagulant prophylaxis had no effect on all-cause mortality (relative risk, 0.97 [CI, 0.79 to 1.19]).

Limitations: 2 of 9 included studies were not double-blind.

Conclusions: Anticoagulant prophylaxis is effective in preventing symptomatic venous thromboembolism during anticoagulant prophylaxis in at-risk hospitalized medical patients. Additional research is needed to determine the risk for venous thromboembolism in these patients after prophylaxis has been stopped.

Editors' Notes Context Anticoagulant prophylaxis of venous thromboembolism in hospitalized patients is better established in surgical practice than in medical practice, in part because of the lack of convincing clinical trial evidence in hospitalized medical patients. Contributions The authors found 9 controlled, randomized trials of currently recommended unfractionated heparin or low-molecular-weight heparin prophylaxis regimens in hospitalized medical patients. Prophylaxis decreased the rate of pulmonary embolism, including fatal pulmonary emboli, by one half—a statistically significant reduction. Prophylaxis did not change other outcomes, including major bleeding. Caution Methods to identify good candidates for prophylaxis do not yet exist. Implications Anticoagulant prophylaxis substantially reduces the risk for venous thromboembolism in hospitalized medical patients. —The Editors

 

Author and Article Information

From McMaster University and St. Joseph's Healthcare, Hamilton, Ontario, Canada.

Acknowledgments: The authors thank Dr. Qilong Yi for his helpful review of and contribution to the manuscript.

Grant Support: Dr. Crowther is a Career Investigator of the Heart and Stroke Foundation of Ontario. Dr. Lim holds a Mentorship award from the Canadian Institutes of Health Research.

Potential Financial Conflicts of Interest: Consultancies: J.D. Douketis (Agen Biomedical), M.A. Crowther (Sanofi-Aventis, Pfizer Inc., Leo Laboratories, GlaxoSmithKline, Organon, Artisian Therapeutics); Honoraria: J.D. Douketis (Sanofi-Aventis, Pfizer Inc., Leo Pharma), M.A. Crowther (Sanofi-Aventis, Pfizer Inc., Leo Laboratories, GlaxoSmithKline, Organon Artisian Therapeutics); Grants received: M.A. Crowther (Sanofi-Aventis, Pfizer Inc., Leo Laboratories, GlaxoSmithKline, Organon, Artisian Therapeutics).

Requests for Single Reprints: James D. Douketis, MD, St. Joseph's Hospital, Room F-544, 50 Charlton Avenue East, Hamilton L8N 4A6, Ontario, Canada; e-mail, jdouket{at}mcmaster.ca.

Current Author Addresses: Drs. Dentali and Gianni: Inusbria University, Viale Borri 57, 21100 Varese, Italy.

Drs. Douketis, Lim, and Crowther: McMaster University, 50 Charleton Avenue East, Hamilton L8N 4A6, Ontario, Canada.

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