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Review
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Bariatric Surgery Versus Non-Surgical Treatment for Obesity: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Affiliations
Review

Bariatric Surgery Versus Non-Surgical Treatment for Obesity: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Viktoria L Gloy et al. BMJ.

Abstract

Objective: To quantify the overall effects of bariatric surgery compared with non-surgical treatment for obesity.

Design: Systematic review and meta-analysis based on a random effects model.

Data sources: Searches of Medline, Embase, and the Cochrane Library from their inception to December 2012 regardless of language or publication status.

Eligibility criteria: 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.

Systematic review registration: PROSPERO CRD42012003317 (www.crd.york.ac.uk/PROSPERO).

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: VLG, AJN, MB, and HCB are supported by an unrestricted grant from Santéuisse and the Gottfried and Julia Bangerter-Rhyner-Foundation. DLB is on the advisory boards of Elsevier PracticeUpdate Cardiology, Medscape Cardiology, and Regado Biosciences; is on the boards of directors of Boston VA Research Institute and Society of Cardiovascular Patient Care; is chair of American Heart Association Get With The Guidelines Steering Committee; has received honoraria from American College of Cardiology (editor, Clinical Trials, Cardiosource), Belvoir Publications (editor in chief, Harvard Heart Letter), Duke Clinical Research Institute (clinical trial steering committees), Population Health Research Institute (clinical trial steering committee), Slack Publications (chief medical editor, Cardiology Today’s Intervention), WebMD (CME steering committees); is senior associate editor, Journal of Invasive Cardiology; is on data monitoring committees of Duke Clinical Research Institute, Mayo Clinic, and Population Health Research Institute; has received research grants from Amarin, AstraZeneca, Bristol-Myers Squibb, Eisai, Ethicon, Medtronic, Sanofi Aventis, the Medicines Company; and has undertaken unfunded research for FlowCo, PLx Pharma, Takeda. PRS has received payment for board membership from Ethicon Endo-Surgery, Surgiquest, Barosense, RemedyMD, and Stryker; consulting fees from Ethicon Endo-Surgery, Stryker, Gore, and Carefusion; payment for expert testimony from Physicians Review of Surgery; lecture fees from Ethi con Endo-Surgery, Allergan, Cinemed, and Quadrant Healthcom; holds a patent for a medical device to enhance weight loss in codevelopment with the Cleveland Clinic; receives royalties from Springer; has an equity interest in Intuitive Surgical, Barosense, Surgiquest, and RemedyMD; and receives institutional grant support (to the Cleveland Clinic) from Ethicon Endo-Surgery and Bard Davol.

Figures

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Fig 1 Results on information search. (*Relevant bariatric surgery techniques were Roux-en-Y gastric bypass, adjustable gastric banding, sleeve gastrectomy, and biliopancreatic diversion with or without duodenal switch)
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Fig 2 Mean change in body weight (kg) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Differences in mean change in body weight calculated by inverse variance statistical method of random effects model)
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Fig 3 Mean change in body weight (kg) after adjustable gastric banding or Roux-en-Y gastric bypass versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus Roux-en-Y gastric bypass. (Differences in mean change in body weight calculated by inverse variance statistical method of random effects model)
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Fig 4 Mean change in (cm) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Differences in mean change in waist circumference calculated by inverse variance statistical method of random effects model)
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Fig 5 Type 2 diabetes remission after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Risk ratios calculated by Mantel-Haenzel statistical method of a random effects model; missing data were not addressed (complete case analysis))
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Fig 6 Metabolic syndrome remission after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Risk ratios calculated by Mantel-Haenzel statistical method of a random effects model; missing data were not addressed (complete case analysis))
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Fig 7 Change in plasma triglyceride concentrations (mmol/L) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (A conversion factor of 0.01129 used to convert values from mg/dL to mmol/L. Differences in mean change in triglyceride concentration calculated by inverse variance statistical method of random effects model)
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Fig 8 Change in plasma total cholesterol concentration (mmol/L) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (A conversion factor of 0.02586 was used to convert values from mg/dL to mmol/L. Differences in mean change in cholesterol concentration calculated by inverse variance statistical method of random effects model)
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Fig 9 Change in high density lipoprotein cholesterol concentrations (mmol/L) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (A conversion factor of 0.02586 was used to convert values from mg/dL to mmol/L. Differences in mean change in concentration calculated by inverse variance statistical method of random effects model)
None
Fig 10 Change in low density lipoprotein cholesterol concentrations (mmol/L) after bariatric surgery versus non-surgical treatment (control) for obesity. (A conversion factor of 0.02586 was used to convert values from mg/dL to mmol/L. Differences in mean change in concentration calculated by inverse variance statistical method of random effects model)
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Fig 11 Change in plasma fasting glucose concentrations (mmol/L) after bariatric surgery versus non-surgical treatment (control) for obesity. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Differences in mean change in concentration calculated by inverse variance statistical method of random effects model)
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Fig 12 Change in glycated haemoglobin HbA1c levels (% points) after bariatric surgery versus non-surgical treatment (control) for obesity. The mean change in HbA1c was pooled for the studies that included diabetic participants only. Subgroup analysis was done for the studies that used adjustable gastric banding versus other bariatric surgery techniques. (Differences in mean change in concentration calculated by inverse variance statistical method of random effects model)

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