title: Volume-outcome association in bariatric surgery: a systematic review.
abstract: OBJECTIVE
  To systematically examine the association between annual hospital and surgeon case volume and patient outcomes in bariatric surgery.
  
  
  BACKGROUND
  Bariatric surgery remains a technically demanding field with significant risk for morbidity and mortality. To mitigate this risk, minimum annual hospital and surgeon case volume requirements are being set and certain hospitals are being designated as "Bariatric Surgery Centers of Excellence." The effects of these interventions on patient outcomes remain unclear.
  
  
  METHODS
  A comprehensive systematic review on volume-outcome association in bariatric surgery was conducted by searching MEDLINE, Cochrane Database of Systematic Reviews, and Evidence Based Medicine Reviews databases. Abstracts of identified articles were reviewed and pertinent full-text versions were retrieved. Manual search of bibliographies was performed and relevant studies were retrieved. Methodological quality assessment and data extraction were completed in a systematic fashion. Pooling of results was not feasible due to the heterogeneity of the studies. A qualitative summary of results is presented.
  
  
  RESULTS
  From a total of 2928 unique citations, 24 studies involving a total of 458,032 patients were selected for review. Two studies were prospective cohorts (level of evidence [LOE] 1), 3 were retrospective cohorts (LOE 3), 2 were retrospective case controls (LOE 3), and 17 were retrospective case series (LOE 4). The overall methodological quality of the reviewed studies was fair. A positive association between annual surgeon volume and patient outcomes was reported in 11 of 13 studies. A positive association between annual hospital volume and patient outcomes was reported in 14 of 17 studies.
  
  
  CONCLUSIONS
  There is strong evidence of improved patient outcomes in the hands of high-volume surgeons and high-volume centers. This study supports the concept of "Bariatric Surgery Center of Excellence" accreditation; however, future research into the quality of care characteristics of successful bariatric programs is recommended. Understanding the characteristics of high-volume surgeons, which lead to improved patient outcomes, also requires further investigation.
authors.affiliation: Department of Surgery, University of Toronto, Toronto, Canada. boris.zevin@utoronto.ca
authors.forename: Boris
authors.initials: B
authors.lastname: Zevin
authors.forename: Rajesh
authors.initials: R
authors.lastname: Aggarwal
authors.forename: Teodor P
authors.initials: TP
authors.lastname: Grantcharov
mesh_terms: D050110:Bariatric Surgery / Q000401:mortality / Q000706:statistics & numerical data*; D006302:Health Services Research; D006801:Humans; D009767:Obesity, Morbid / Q000401:mortality / Q000601:surgery; D017063:Outcome Assessment, Health Care