title: Weight loss before bariatric surgery and postoperative complications: data from the Scandinavian Obesity Registry (SOReg).
abstract: BACKGROUND
  A preoperative weight-reducing regimen is usually adhered to in most centers performing bariatric surgery for obesity. The potential to reduce postoperative complications by such a routine is yet to be defined.
  
  
  METHODS
  Data on 22,327 patients undergoing primary gastric bypass from January 1, 2008, to June 30, 2012, were analyzed.
  
  
  RESULTS
  In all patients, median preoperative total weight change was -4.8%. Corresponding values in the 25th, 50th, and 75th percentile were 0.5, -4.7, and -9.5%, respectively. Complications were noted in 9.1% of the patients. When comparing patients in the 75th with those in the 25th percentile of preoperative weight loss, the risk of complications was reduced by 13%. For specific complications, the corresponding risks were reduced for anastomotic leakage by 24%, for deep infection/abscess by 37%, and for minor wound complications by 54%. Similarly, however, less pronounced risk reductions were found when comparing patients in the 50th with those in the 25th percentile of preoperative weight loss. For patients in the highest range of body mass index (BMI), the risk reduction associated with preoperative weight loss was statistically significant for all analyzed complications, whereas corresponding risk reductions were only occasionally encountered and less pronounced in patients with lower BMI.
  
  
  CONCLUSIONS
  Weight loss before bariatric surgery is associated with marked reduction of risk of postoperative complications. Moreover, the degree of risk reduction seems to be related to amount of weight lost and patients in the higher range of BMI are likely to benefit most from preoperative weight reduction.
authors.affiliation: *Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital and Department of Surgery, Ersta Hospital, Stockholm, Sweden †Department of Surgery, Capio, St Görans Hospital, Stockholm, Sweden.
authors.forename: Claes
authors.initials: C
authors.lastname: Anderin
authors.forename: Ulf O
authors.initials: UO
authors.lastname: Gustafsson
authors.forename: Niklas
authors.initials: N
authors.lastname: Heijbel
authors.forename: Anders
authors.initials: A
authors.lastname: Thorell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D050110:Bariatric Surgery / Q000706:statistics & numerical data; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000517:prevention & control; D011300:Preoperative Care; D012042:Registries; D040242:Risk Reduction Behavior; D013548:Sweden / Q000453:epidemiology; D015431:Weight Loss; D055815:Young Adult