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Cover of Bariatric Surgery and Nonsurgical Therapy in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2

Bariatric Surgery and Nonsurgical Therapy in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2

Comparative Effectiveness Reviews, No. 82

Investigators: Margaret A Maglione, MPP, Melinda Maggard Gibbons, MD, Masha Livhits, MD, Brett Ewing, MS, Jianhui Hu, MPP, Alicia Ruelaz Maher, MD, Zhaoping Li, MD PhD, Tanja Perry, BHM, and Paul G Shekelle, MD, PhD.

Southern California Evidence-based Practice Center
Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Jun.
Report No.: 12(13)-EHC139-EF
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Structured Abstract


To systematically review the scientific evidence on efficacy, safety, and comparative effectiveness of various types of bariatric surgery for treating adult patients with a body mass index (BMI) of 30.0 to 34.9 kg/m2 and diabetes or impaired glucose tolerance (IGT) and to compare effectiveness of surgery versus nonsurgical interventions in this population.

Data sources:

Systematic reviews, case series, cohort, case control studies and controlled trials, found through searching PubMed®, Embase, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Abstracts of Reviews of Effects (DARE), and Clinicaltrials.gov through March, 2012.

Review methods:

To be included, studies had to report on laparoscopic adjustable gastric banding (LAGB), Roux-en-Y gastric bypass (RYGB), biliopancreatic diversion with duodenal switch (BPD), sleeve gastrectomy (SG), or nonsurgical treatment, and had to include patients with a BMI of at least 30 kg/m2 but less than 35 kg/m2 with diabetes or IGT. The following studies were excluded: (1) those with no outcomes of efficacy, effectiveness, or safety/adverse events; (2) nonsurgical studies with less than one year followup; (3) nonsurgical studies already included in previous systematic reviews; and (4) studies with a sample size of less than three. Two reviewers, each trained in the critical analysis of scientific literature, independently reviewed and abstracted each study.


We found only 24 studies reporting bariatric surgery results in this specific target population. Two were trials comparing different procedures, three were trials of surgical versus nonsurgical interventions, and the rest were observational studies. Both weight and blood glucose improved significantly for surgery patients in the trials. In the observational studies, surgery patients showed much greater weight loss at 1 year than reported in systematic reviews and randomized controlled trials (RCTs) on diet, exercise, medication, and other behavioral interventions. While both behavioral interventions and medications lowered HbA1c (glycosylated hemoglobin) levels significantly, the decreases reported in surgery patients were much greater. Improvements in blood glucose measures were reported as early as one month postsurgery. Improvements in hypertension, low-density lipoprotein (LDL) cholesterol, and triglycerides were also reported in some studies. Short-term rates of adverse events associated with bariatric surgery were relatively low. One death, a case of sepsis at 20 months in an LAGB patient, was reported. Short-term complications were minor and tended not to require major intervention. Due to the dearth of long-term studies of bariatric surgery in this particular target population, few data exist about long-term adverse effects, and we found no evidence regarding major clinical endpoints such as all-cause mortality, cardiovascular mortality and morbidity, and peripheral arterial disease.


According to blood glucose outcomes, there is moderate strength evidence of efficacy for RYGB, LAGB, and SG as treatment for diabetes and IGT in patients with a BMI between 30 kg/m2 and 35 kg/m2 in the short term (up to 2 years). The strength of evidence for BPD is rated low because there are fewer studies, and these have smaller sample sizes. Evidence on comparative effectiveness of surgical procedures is insufficient. Short-term adverse events are relatively minor; strength of evidence is low due to small sample size with low power to detect rare events. Strength of evidence is insufficient regarding adverse events in the long-term (2 years or more postsurgery). Longitudinal studies of bariatric surgery patients are needed to assess overall safety and comparative effectiveness regarding diabetes-related morbidity such as kidney failure and blindness.


Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services1, Contract No. 290-2007-10062-I. Prepared by: Southern California Evidence-based Practice Center, Santa Monica, CA

Suggested citation:

Maglione MA, Maggard Gibbons M, Livhits M, Ewing B, Hu J, Ruelaz Maher A, Li Z, Perry T, Shekelle PG. Bariatric Surgery and Nonsurgical Therapy in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2. Comparative Effectiveness Review No. 82. (Prepared by the Southern California Evidence-based Practice Center under Contract No. 290-2007-10062-I.) AHRQ Publication No. 12(13)-EHC139-EF. Rockville, MD: Agency for Healthcare Research and Quality. June 2013. www.effectivehealthcare.ahrq.gov/reports/final.cfm.

This report is based on research conducted by the Southern California Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2007-10062-I). The findings and conclusions in this document are those of the author(s), who are responsible for its contents; the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help health care decisionmakers—patients and clinicians, health system leaders, and policymakers, among others—make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances presented by individual patients.

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

None of the investigators have any affiliations or financial involvement that conflicts with the material presented in this report.


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