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Invited Critique
Nov 2012

Venous Thromboembolism Prophylaxis: One Size Does Not Fit All: Comment on “Comparative Effectiveness of Unfractionated and Low-Molecular-Weight Heparin for Prevention of Venous Thromboembolism Following Bariatric Surgery”

Author Affiliations

Author Affiliation: Department of Surgery, University of California, San Francisco.

Arch Surg. 2012;147(11):998-999. doi:10.1001/archsurg.2012.2318

For the past 30 years, based on multiple studies involving thousands of general surgery patients, the standard method of preventing VTE complications in surgical patients was to administer UF heparin (5000 U subcutaneously) 2 hours prior to the surgical procedure and continue that dose every 12 hours until the patient was ambulatory.1,2 More recently, however, several high-risk patient groups have been identified in whom this type of prophylaxis is inadequate. These groups include trauma, orthopedics, neurologic, and, based on the article by Birkmeyer et al,3 bariatric surgical patients. The VTE risk may be as high as 3% among patients undergoing bariatric surgery and pulmonary embolism is the number one cause of death in this group. Low-molecular-weight heparin has a greater affinity for antithrombin than UF heparin and a greater bioavailability through easier subcutaneous absorption, which may be particularly important in obese patients. In several studies, LMW heparin has been shown to be more effective in preventing VTE than UF heparin.4-7 The data compiled through the MBSC suggest that patients who received LMW heparin both preoperatively and postoperatively had a 66% lower VTE rate than those who received UF heparin, with an acceptable bleeding risk. In addition to decreasing morbidity and mortality, prevention of VTE may have financial implications for providers, because the Centers for Medicare & Medicaid Services considers deep vein thrombosis a preventable complication.