title: Apixaban versus enoxaparin in the prevention of venous thromboembolism following total knee arthroplasty: a single-centre, single-surgeon, retrospective analysis.
abstract: BACKGROUND
  There is a high risk of developing venous thromboembolism (VTE) following total knee arthroplasty (TKA). Conventional thromboprophylactic agents have limitations, such as route of administration, the need for monitoring, narrow therapeutic windows and interactions. Apixaban is a new oral anticoagulant with the potential to overcome these limitations.
  
  
  OBJECTIVE
  To report the efficacy and safety of apixaban and low-molecular-weight heparin, enoxaparin, in VTE prophylaxis following TKA.
  
  
  METHODS
  This single-centre, single-surgeon, retrospective analysis included 506 consecutive patients who underwent TKA between 2009 and 2015 and received enoxaparin or apixaban as thromboprophylaxis. Baseline characteristics of patients, in-hospital rates of VTE, total DVT, proximal or distal DVT, pulmonary embolism, bleeding outcomes and mortality were compared between the two groups.
  
  
  RESULTS
  In-hospital VTE occurred in 22 (8.9%) patients in the enoxaparin group and 11 (4.5%) patients in the apixaban group (P = 0.049). Nine (3.6%) patients in the enoxaparin group and one (0.4%) in the apixaban group experienced a postoperative drop in haemoglobin ≥20 g/L that either necessitated transfusion of ≥2 units blood, caused haemodynamic instability or both (P = 0.020). Thirty-five patients experienced other bleeding events, with 25 (9.9%) in the enoxaparin group and 10 (4.0%) in the apixaban group (P = 0.009). There were no statistically significant differences in rates of total DVT, proximal or distal DVT, pulmonary embolism or mortality between the groups.
  
  
  CONCLUSIONS
  Compared with enoxaparin, thromboprophylaxis with apixaban resulted in a lower VTE incidence and fewer haemorrhagic complications.
authors.affiliation: School of Medicine, The University of Notre Dame, Sydney, New South Wales, Australia. danika.king07@gmail.com.
authors.forename: D A L
authors.initials: DA
authors.lastname: King
authors.affiliation: School of Medicine, The University of Notre Dame, Sydney, New South Wales, Australia.
authors.forename: R E
authors.initials: RE
authors.lastname: Pow
authors.affiliation: Department of Orthopaedic Surgery, Mater Hospital, Sydney, New South Wales, Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: Dickison
authors.affiliation: School of Medicine, The University of Notre Dame, Sydney, New South Wales, Australia.|Department of Cardiovascular Medicine, Mater Hospital, Sydney, New South Wales, Australia.
authors.forename: P R
authors.initials: PR
authors.lastname: Vale
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001315:Australia; D017984:Enoxaparin / Q000009:adverse effects / Q000627:therapeutic use*; D065427:Factor Xa Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006470:Hemorrhage / Q000453:epidemiology / Q000209:etiology; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000209:etiology; D011720:Pyrazoles / Q000009:adverse effects / Q000627:therapeutic use*; D011728:Pyridones / Q000009:adverse effects / Q000627:therapeutic use*; D012189:Retrospective Studies; D054556:Venous Thromboembolism / Q000453:epidemiology / Q000517:prevention & control*
chemical_list: D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D011720:Pyrazoles; D011728:Pyridones; C522181:apixaban
keywords: apixaban; enoxaparin; knee arthroplasty; prophylaxis; venous thromboembolism