title: Preoperative placement of inferior vena cava filters and outcomes after gastric bypass surgery.
abstract: OBJECTIVE
  To assess relationships between inferior vena cava (IVC) filter placement and complications within 30 days of gastric bypass surgery.
  
  
  BACKGROUND
  IVC filters are increasingly being used as prophylaxis against postoperative pulmonary embolism in patients undergoing bariatric surgery, despite a lack of evidence of effectiveness.
  
  
  METHODS
  On the basis of data from a prospective clinical registry involving 20 Michigan hospitals, we identified 6376 patients undergoing gastric bypass surgery between 2006 and 2008. We then assessed relationships between IVC filter placement and complications within 30 days of surgery. We used propensity scores and fixed effects logistic regression to control for potential selection bias.
  
  
  RESULTS
  A total of 542 gastric bypass patients (8.5%) underwent preoperative IVC filter placement, most of whom (65%) had no history of venous thromboembolism. The use of IVC filters for gastric bypass patients varied widely across hospitals (range, 0%-34%). IVC filter patients did not have reduced rates of postoperative venous thromboembolism (adjusted odds ratio [OR], = 1.28; 95% confidence interval [CI], 0.51-3.21), serious complications (adjusted OR, = 1.40; 95% CI, 0.91-2.16), or death/permanent disability (adjusted OR, = 2.49; 95% CI, 0.99-6.26). More than half (57%) of the IVC filter patients in the latter group had a fatal pulmonary embolism or complications directly related to the IVC filter itself, including filter migration or thrombosis of the vena cava. In subgroup analyses, we were unable to identify any patient group for whom IVC filters were associated with improved outcomes.
  
  
  CONCLUSIONS
  Prophylactic IVC filters for gastric bypass surgery do not reduce the risk of pulmonary embolism and may lead to additional complications.
authors.affiliation: Department of Surgery, Michigan Surgical Collaboration for Outcomes Research and Evaluation, University of Michigan, Ann Arbor, MI, USA. nbirkmey@med.umich.edu
authors.forename: Nancy J O
authors.initials: NJ
authors.lastname: Birkmeyer
authors.forename: David
authors.initials: D
authors.lastname: Share
authors.forename: Onur
authors.initials: O
authors.lastname: Baser
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Carlin
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Finks
authors.forename: Carl M
authors.initials: CM
authors.lastname: Pesta
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Genaw
authors.forename: John D
authors.initials: JD
authors.lastname: Birkmeyer
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control*; D011300:Preoperative Care; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000209:etiology / Q000517:prevention & control*; D012042:Registries; D012307:Risk Factors; D016896:Treatment Outcome; D016306:Vena Cava Filters