title: Comparative effectiveness of unfractionated and low-molecular-weight heparin for prevention of venous thromboembolism following bariatric surgery.
abstract: OBJECTIVE
  To evaluate the effectiveness and safety of 3 predominant venous thromboembolism (VTE) prophylaxis strategies among patients undergoing bariatric surgery.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  The Michigan Bariatric Surgery Collaborative, a statewide clinical registry and quality improvement program.
  
  
  METHODS
  Twenty-four thousand seven hundred seventy-seven patients undergoing bariatric surgery between 2007 and 2012.
  
  
  METHODS
  Unfractionated heparin preoperatively and postoperatively (UF/UF), UF heparin preoperatively and low-molecular-weight heparin postoperatively (UF/LMW), and LMW heparin preoperatively and postoperatively (LMW/LMW).
  
  
  METHODS
  Rates of VTE, hemorrhage, and serious hemorrhage (requiring >4 U of blood products or reoperation) occurring within 30 days of surgery.
  
  
  RESULTS
  Overall, adjusted rates of VTE were significantly lower for the LMW/LMW (0.25%; P < .001) and UF/LMW (0.29%; P = .03) treatment groups compared with the UF/UF group (0.68%). While UF/LMW (0.22%; P = .006) and LMW/LMW (0.21%; P < .001) were similarly effective in patients at low risk of VTE (predicted risk <1%), LMW/LMW (1.46%; P = .10) seemed more effective than UF/LMW (2.36%; P = .90) for high-risk (predicted risk ≥1%) patients. There were no significant differences in rates of hemorrhage or serious hemorrhage among the treatment strategies.
  
  
  CONCLUSIONS
  Low-molecular-weight heparin is more effective than UF heparin for the prevention of postoperative VTE among patients undergoing bariatric surgery and does not increase rates of bleeding.
authors.forename: Nancy J O
authors.initials: NJ
authors.lastname: Birkmeyer
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Finks
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Carlin
authors.forename: David L
authors.initials: DL
authors.lastname: Chengelis
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Krause
authors.forename: Abdelkader A
authors.initials: AA
authors.lastname: Hawasli
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Genaw
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: English
authors.forename: Jon L
authors.initials: JL
authors.lastname: Schram
authors.forename: John D
authors.initials: JD
authors.lastname: Birkmeyer
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects; D050110:Bariatric Surgery / Q000009:adverse effects* / Q000379:methods; D015992:Body Mass Index; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006493:Heparin / Q000008:administration & dosage* / Q000009:adverse effects; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009767:Obesity, Morbid / Q000175:diagnosis / Q000601:surgery; D016017:Odds Ratio; D011182:Postoperative Care / Q000379:methods; D011183:Postoperative Complications / Q000517:prevention & control; D011300:Preoperative Care / Q000379:methods; D011322:Primary Prevention / Q000379:methods; D011655:Pulmonary Embolism / Q000517:prevention & control*; D012042:Registries; D012189:Retrospective Studies; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin