title: Weight loss before gastric bypass and postoperative weight change: data from the Scandinavian Obesity Registry (SOReg).
abstract: BACKGROUND
  Weight loss before bariatric surgery has been found to be associated with reduced rates of postoperative complications.
  
  
  OBJECTIVE
  To evaluate whether preoperative weight loss was also associated with improved postoperative weight loss over time and if this was dependent on preoperative body mass index (BMI).
  
  
  METHODS
  Data from the Swedish national registry for bariatric surgery.
  
  
  METHODS
  Out of 20,564 patients undergoing primary gastric bypass from January 1, 2008 to November 30, 2011, 9570 with complete data on preoperative weight loss and 2 years postoperative weight loss were analyzed.
  
  
  RESULTS
  Total preoperative weight loss in the 25th, 50th, and 75th percentiles was 0%, 4.5%, and 8.6%, respectively. When comparing patients in the 50th percentile for preoperative weight loss with those in the 25th percentile, total postoperative weight loss was 5.0% and 5.3% higher at 1 and 2 years, respectively (P<.001). Corresponding values for patients in the 75th percentile for preoperative weight loss were 11.8% and 10.1% (P< .001). For patients in the 75th percentile of preoperative BMI (>45.7 kg/m(2)) the effect was even more pronounced. Thus, in this group of patients and within the 75th percentile for preoperative weight loss, the total weight reduction after 1 and 2 years was 15.2% and 13.6% higher compared with patients in the 25th percentile for preoperative weight loss.
  
  
  CONCLUSIONS
  In this Swedish national bariatric registry data set, weight loss before gastric bypass was associated with sustained improved postoperative weight reduction. Moreover, there was a relationship between the degree of pre- and postoperative weight loss and the relationship was stronger in patients with high BMI.
authors.affiliation: Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden; Department of Surgery, Ersta Hospital, Stockholm, Sweden. Electronic address: peter.gerber@erstadiakoni.se.
authors.forename: Peter
authors.initials: P
authors.lastname: Gerber
authors.affiliation: Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden; Department of Surgery, Ersta Hospital, Stockholm, Sweden.
authors.forename: Claes
authors.initials: C
authors.lastname: Anderin
authors.affiliation: Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden; Department of Surgery, Danderyds Hospital, Stockholm, Sweden.
authors.forename: Ulf O
authors.initials: UO
authors.lastname: Gustafsson
authors.affiliation: Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden; Department of Surgery, Ersta Hospital, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Thorell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D061887:Conversion to Open Surgery / Q000706:statistics & numerical data; D005260:Female; D015390:Gastric Bypass / Q000706:statistics & numerical data*; D006801:Humans; D010535:Laparoscopy / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000601:surgery*; D061646:Operative Time; D011182:Postoperative Care; D011300:Preoperative Care; D011446:Prospective Studies; D012042:Registries; D013548:Sweden / Q000453:epidemiology; D015431:Weight Loss / Q000502:physiology*; D055815:Young Adult
keywords: Gastric Bypass; Laparoscopic; Post operative weight loss; Preoperative low calorie diet; Scandinavian Obesity Surgery Registry