title: Apixaban or enoxaparin for thromboprophylaxis after knee replacement.
abstract: BACKGROUND
  The optimal strategy for thromboprophylaxis after major joint replacement has not been established. Low-molecular-weight heparins such as enoxaparin predominantly target factor Xa but to some extent also inhibit thrombin. Apixaban, a specific factor Xa inhibitor, may provide effective thromboprophylaxis with a low risk of bleeding and improved ease of use.
  
  
  METHODS
  In a double-blind, double-dummy study, we randomly assigned patients undergoing total knee replacement to receive 2.5 mg of apixaban orally twice daily or 30 mg of enoxaparin subcutaneously every 12 hours. Both medications were started 12 to 24 hours after surgery and continued for 10 to 14 days. Bilateral venography was then performed. The primary efficacy outcome was a composite of asymptomatic and symptomatic deep-vein thrombosis, nonfatal pulmonary embolism, and death from any cause during treatment. Patients were followed for 60 days after anticoagulation therapy was stopped.
  
  
  RESULTS
  A total of 3195 patients underwent randomization, with 1599 assigned to the apixaban group and 1596 to the enoxaparin group; 908 subjects were not eligible for the efficacy analysis. The overall rate of primary events was much lower than anticipated. The rate of the primary efficacy outcome was 9.0% with apixaban as compared with 8.8% with enoxaparin (relative risk, 1.02; 95% confidence interval, 0.78 to 1.32). The composite incidence of major bleeding and clinically relevant nonmajor bleeding was 2.9% with apixaban and 4.3% with enoxaparin (P=0.03).
  
  
  CONCLUSIONS
  As compared with enoxaparin for efficacy of thromboprophylaxis after knee replacement, apixaban did not meet the prespecified statistical criteria for noninferiority, but its use was associated with lower rates of clinically relevant bleeding and it had a similar adverse-event profile. (ClinicalTrials.gov number, NCT00371683.)
authors: Department of Orthopedics, Spine Clinic, Clinical Trial Unit, Hørsholm Hospital, University of Copenhagen, Hørsholm, Denmark.
authors: Michael Rud
authors: MR
authors: Lassen
authors: Gary E
authors: GE
authors: Raskob
authors: Alexander
authors: A
authors: Gallus
authors: Graham
authors: G
authors: Pineo
authors: Dalei
authors: D
authors: Chen
authors: Ronald J
authors: RJ
authors: Portman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D019645:Arthroplasty, Replacement, Knee; D004311:Double-Blind Method; D017984:Enoxaparin / Q000009:adverse effects / Q000627:therapeutic use*; D065427:Factor Xa Inhibitors; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D011183:Postoperative Complications / Q000517:prevention & control*; D011720:Pyrazoles / Q000009:adverse effects / Q000627:therapeutic use*; D011728:Pyridones / Q000009:adverse effects / Q000627:therapeutic use*; D054556:Venous Thromboembolism / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D011720:Pyrazoles; D011728:Pyridones; C522181:apixaban