title: Prevention of venous thromboembolism with new oral anticoagulants versus standard pharmacological treatment in acute medically ill patients: a systematic review and meta-analysis.
abstract: BACKGROUND
  Venous thromboembolism (VTE) is a common and potentially avoidable cause of morbidity and mortality in patients hospitalized for acute medical illness.
  
  
  OBJECTIVE
  Our objective was to conduct a systematic review of studies that assessed the efficacy and safety of new oral anticoagulant (OAC) drugs versus standard pharmacological drugs and/or placebo in prevention of VTE in acute medically ill patients.
  
  
  METHODS
  PubMed.org and ClinicalTrials.gov databases were searched to identify studies that evaluated the efficacy and safety of a new OAC versus the standard pharmacological treatment and/or placebo in the prevention of VTE in medically ill patients. Relative risks (RR), weighted means and 95% CIs were calculated. Statistical heterogeneity was evaluated using Chi2 and I2 statistics. Two studies were included in the meta-analysis. The primary outcome in both studies was the composite of VTE-related death, symptomatic non-fatal pulmonary embolism (PE), symptomatic deep venous thrombosis (DVT) and asymptomatic proximal DVT. Both studies compared a factor (F)Xa inhibitor with enoxaparin in standard short-term thromboprophylaxis followed by a period where the FXa inhibitor was compared with placebo as prolonged thromboprophylaxis in medically ill patients. The primary major safety outcome in both studies was a composite of treatment-related major bleeding and clinically relevant non-major bleeding. A total of 14 629 patients were randomized.
  
  
  RESULTS
  Compared with subjects treated with enoxaparin followed by placebo, the RR of the primary outcome during the prolonged treatment period was 0.79 (95% CI 0.66, 0.94), the RR for the primary outcome during the first short-term treatment period was 1.03 (95% CI 0.81, 1.31). For major bleeding during the prolonged treatment period, the RR was 2.69 (95% CI 1.65, 4.39) for patients treated with an FXa inhibitor compared with enoxaparin/placebo. For major bleeding during the shorter treatment period, the RR was 2.01 (95% CI 1.10, 3.65) in favour of enoxaparin.
  
  
  CONCLUSIONS
  In acute medically ill patients, prolonged thromboprophylaxis with an oral FXa inhibitor is more protective than regular short-term treatment with enoxaparin. However, treatment with FXa inhibitors is significantly associated with major bleeding, both in long- and short-term treatment compared with enoxaparin.
authors.affiliation: University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK.
authors.forename: Ida Ehlers
authors.initials: IE
authors.lastname: Albertsen
authors.forename: Torben Bjerregaard
authors.initials: TB
authors.lastname: Larsen
authors.forename: Lars Hvilsted
authors.initials: LH
authors.lastname: Rasmussen
authors.forename: Thure Filskov
authors.initials: TF
authors.lastname: Overvad
authors.forename: Gregory Y H
authors.initials: GY
authors.lastname: Lip
mesh_terms: D000208:Acute Disease; D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D017984:Enoxaparin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D065427:Factor Xa Inhibitors; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000097:blood / Q000209:etiology / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors