title: Effect of preoperative weight loss in bariatric surgical patients: a systematic review.
abstract: BACKGROUND
  The potential benefit of preoperative weight loss in patients undergoing bariatric surgery has led many bariatric surgeons to recommend an aggressive weight reduction regimen to their patients. Some surgeons might withhold bariatric procedures if a certain threshold of preoperative weight loss is not achieved. It is unclear whether this practice has any scientific evidence supporting it. Our study aimed to examine the current evidence surrounding this issue in a systematic review. The setting was a university hospital.
  
  
  METHODS
  A systematic search of multiple databases, including MEDLINE, Google Scholar, EMBASE, the Cochrane Library, and conference proceedings were reviewed, yielding a final total of 27 studies. Of the 27 studies, 7 were prospective studies (2 randomized controlled trials from the same patient population), 14 were retrospective studies (2 chart reviews from the same patient population), 1 was an editorial, and a number were conference presentations.
  
  
  RESULTS
  A total of 17 trials, including approximately 4611 patients, deemed preoperative weight loss beneficial, and 10 studies, including 2075 patients, deemed preoperative weight loss to be of no benefit. The operative time was 12.5 minutes shorter for the preoperative weight loss patients undergoing laparoscopic Roux-en-Y gastric bypass. With regard to the effects of preoperative weight loss on postoperative weight loss, 9 studies (39%) reported a positive correlation, and 15 (62.5%) reported no benefit. Nine studies reporting perioperative complications (852 patients) revealed no difference in the complication rates, and 2 studies (1234 patients) suggested a significant decrease was associated with preoperative weight loss.
  
  
  CONCLUSIONS
  This systematic review suggests little evidence is available to support or refute the routine use of preoperative weight reduction in bariatric surgery. Clearly, a large-scale, multicenter, randomized, controlled trial with sufficient power is necessary to clarify this significant aspect of preoperative care.
authors: Department of Surgery, University of Calgary Faculty of Medicine, Calgary, Alberta, Canada.
authors: Scott
authors: S
authors: Cassie
authors: Carlos
authors: C
authors: Menezes
authors: Daniel W
authors: DW
authors: Birch
authors: Xinzhe
authors: X
authors: Shi
authors: Shahzeer
authors: S
authors: Karmali
mesh_terms: D050110:Bariatric Surgery / Q000379:methods* / Q000706:statistics & numerical data; D004812:Epidemiologic Methods; D005260:Female; D015390:Gastric Bypass / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D010535:Laparoscopy / Q000379:methods* / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology; D011300:Preoperative Care / Q000379:methods*; D015431:Weight Loss / Q000502:physiology*