title: Bariatric surgery versus non-surgical treatment for obesity: a systematic review and meta-analysis of randomised controlled trials.
abstract: OBJECTIVE
  To quantify the overall effects of bariatric surgery compared with non-surgical treatment for obesity.
  
  
  METHODS
  Systematic review and meta-analysis based on a random effects model.
  
  
  METHODS
  Searches of Medline, Embase, and the Cochrane Library from their inception to December 2012 regardless of language or publication status.
  
  
  METHODS
  Eligible studies were randomised controlled trials with ≥ 6 months of follow-up that included individuals with a body mass index ≥ 30, compared current bariatric surgery techniques with non-surgical treatment, and reported on body weight, cardiovascular risk factors, quality of life, or adverse events.
  
  
  RESULTS
  The meta-analysis included 11 studies with 796 individuals (range of mean body mass index at baseline 30-52). Individuals allocated to bariatric surgery lost more body weight (mean difference -26 kg (95% confidence interval -31 to -21)) compared with non-surgical treatment, had a higher remission rate of type 2 diabetes (relative risk 22.1 (3.2 to 154.3) in a complete case analysis; 5.3 (1.8 to 15.8) in a conservative analysis assuming diabetes remission in all non-surgically treated individuals with missing data) and metabolic syndrome (relative risk 2.4 (1.6 to 3.6) in complete case analysis; 1.5 (0.9 to 2.3) in conservative analysis), greater improvements in quality of life and reductions in medicine use (no pooled data). Plasma triglyceride concentrations decreased more (mean difference -0.7 mmol/L (-1.0 to -0.4) and high density lipoprotein cholesterol concentrations increased more (mean difference 0.21 mmol/L (0.1 to 0.3)). Changes in blood pressure and total or low density lipoprotein cholesterol concentrations were not significantly different. There were no cardiovascular events or deaths reported after bariatric surgery. The most common adverse events after bariatric surgery were iron deficiency anaemia (15% of individuals undergoing malabsorptive bariatric surgery) and reoperations (8%).
  
  
  CONCLUSIONS
  Compared with non-surgical treatment of obesity, bariatric surgery leads to greater body weight loss and higher remission rates of type 2 diabetes and metabolic syndrome. However, results are limited to two years of follow-up and based on a small number of studies and individuals.
  
  
  BACKGROUND
  PROSPERO CRD42012003317 (www.crd.york.ac.uk/PROSPERO).
authors.affiliation: Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Hebelstrasse 10, CH-4031 Basel, Switzerland.
authors.forename: Viktoria L
authors.initials: VL
authors.lastname: Gloy
authors.forename: Matthias
authors.initials: M
authors.lastname: Briel
authors.forename: Deepak L
authors.initials: DL
authors.lastname: Bhatt
authors.forename: Sangeeta R
authors.initials: SR
authors.lastname: Kashyap
authors.forename: Philip R
authors.initials: PR
authors.lastname: Schauer
authors.forename: Geltrude
authors.initials: G
authors.lastname: Mingrone
authors.forename: Heiner C
authors.initials: HC
authors.lastname: Bucher
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Nordmann
mesh_terms: D050110:Bariatric Surgery; D015992:Body Mass Index; D006801:Humans; D009765:Obesity / Q000150:complications / Q000378:metabolism / Q000628:therapy*; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence; D015431:Weight Loss