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Bariatric surgery versus non-surgical treatment for obesity
  1. Viktoria L Gloy1,
  2. Matthias Briel1,2,
  3. Deepak L Bhatt3,
  4. Sangeeta R Kashyap4,
  5. Philip R Schauer5,
  6. Geltrude Mingrone6,
  7. Heiner C Bucher1,
  8. Alain J Nordmann1
  1. 1Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, Hebelstrasse 10, CH-4031 Basel, Switzerland
  2. 2Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada
  3. 3VA Boston Healthcare System, Brigham and Women's Hospital, and Harvard Medical School, Boston, USA
  4. 4Endocrinology Institute, Cleveland Clinic, Cleveland, USA
  5. 5Bariatric & Metabolic Institute, Cleveland Clinic, Cleveland, USA
  6. 6Department of Internal Medicine, Università Cattolica S. Cuore, Rome, Italy
  1. Correspondence to : V L Gloy; Viktoria.Gloy{at}


STUDY QUESTION What are the summary effects of bariatric surgery compared with non-surgical treatment for obesity on body weight loss, comorbidities, adverse events, and quality of life?

SUMMARY ANSWER Bariatric surgery is more effective in inducing body weight loss and remission of type 2 diabetes and metabolic syndrome after a maximal follow-up of 2 years, no cardiovascular events or deaths were reported after bariatric surgery, and the most common adverse events after bariatric surgery were iron deficiency anaemia and reoperations.

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Selection criteria for studies

We searched Medline, Embase, and the Cochrane Library from their inception to June 2013. 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 (Roux-en-Y gastric bypass, adjustable gastric banding, sleeve gastrectomy, and biliopancreatic diversion) with non-surgical treatment for obesity (diet, weight reducing medication, behavioural therapy, or any combination thereof), and reported on body weight, comorbidities, quality of life, or adverse events.

Primary outcome(s)

Body weight loss; remission rates of type 2 diabetes, metabolic syndrome, or hypertension; and reduction in use of medications, adverse events, and quality of life.

Main results and role of chance

The meta-analysis included 11 studies with 796 individuals. 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 risks 22.1 (3.2 to 154.3) in a complete case analysis and 5.3 (1.8 to 15.8) in a conservative analysis assuming diabetes remission in all non-surgically treated individuals with missing data), a higher remission rate of metabolic syndrome (relative risks 2.4 (1.6 to 3.6) in complete case analysis and 1.5 (0.9 to 2.3) in conservative analysis), and greater improvements in quality of life and reductions in the use of medication (no pooled data). Hypertension remission was not addressed by any of the studies. There were no cardiovascular events or death. The most common adverse events after bariatric surgery were iron deficiency anaemia (15% of individuals undergoing malabsorptive bariatric surgery) and reoperations (8%).

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  • This is a summary of a paper that was published on as BMJ 2013;347:f5934

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