title: Prevention of venous thromboembolism in orthopedic surgery with vitamin K antagonists: a meta-analysis.
abstract: BACKGROUND
  The benefit-to-risk ratio of vitamin K antagonists (VKA), relative to active comparators, especially low-molecular-weight heparins (LMWH), for preventing venous thromboembolism in patients undergoing major orthopedic surgery is debated.
  
  
  OBJECTIVE
  We performed a meta-analysis of all randomized trials in orthopedic surgery comparing adjusted doses of VKA to control treatments.
  
  
  METHODS
  An exhaustive literature search, both manual and computer-assisted, was performed. Studies were selected on the basis of randomization procedure (VKA vs. a control group). At least one of the following outcome measures was to be evaluated: deep vein thrombosis (DVT), pulmonary embolism (PE), death, major hemorrhage or wound hematoma. Four reviewers assessed each article to determine eligibility for inclusion and outcome measures.
  
  
  RESULTS
  VKAs were more effective than placebo or no treatment in reducing DVT [567 patients, relative risk (RR) = 0.56, 95% confidence interval (CI) 0.37, 0.84, P < 0.01] and clinical PE (651 patients, RR = 0.23, 95% CI 0.09, 0.59, P < 0.01). These results were obtained at the cost of a higher rate of wound hematoma (162 patients, RR = 2.91, 95% CI 1.09, 7.75, P = 0.03). VKAs were also more effective than intermittent pneumatic compression (534 patients, RR = 0.46, 95% CI 0.25, 0.82, P = 0.009) in preventing proximal DVT. In contrast, VKAs were less effective than LMWH in preventing total DVT and proximal DVT (9822 patients, RR = 1.51, 95% CI 1.27, 1.79, P < 0.001; and 6131 patients, RR = 1.51, 95% CI 1.04, 2.17, P = 0.028, respectively). The differences between VKA and LMWH in major hemorrhage and wound hematoma were not significant.
  
  
  CONCLUSIONS
  In patients undergoing major orthopedic surgery, VKAs are less effective than LMWH, without any significant difference in the bleeding risk.
authors.affiliation: Department of Anesthesia, University Hospital Bellevue, Saint-Etienne, France.
authors.forename: P
authors.initials: P
authors.lastname: Mismetti
authors.forename: S
authors.initials: S
authors.lastname: Laporte
authors.forename: P
authors.initials: P
authors.lastname: Zufferey
authors.forename: M
authors.initials: M
authors.lastname: Epinat
authors.forename: H
authors.initials: H
authors.lastname: Decousus
authors.forename: M
authors.initials: M
authors.lastname: Cucherat
mesh_terms: D005343:Fibrinolytic Agents / Q000009:adverse effects / Q000592:standards / Q000627:therapeutic use*; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D019637:Orthopedic Procedures / Q000009:adverse effects*; D011183:Postoperative Complications / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic; D015996:Survival Rate; D013810:Therapeutic Equivalency; D013923:Thromboembolism / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control*; D020246:Venous Thrombosis / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control*; D014812:Vitamin K / Q000037:antagonists & inhibitors*
chemical_list: D005343:Fibrinolytic Agents; D014812:Vitamin K