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Literature review

Insufficient evidence for surgery if BMI 30-35

More evidence needed regarding the long-term benefits and risks of surgery

There is insufficient evidence to support bariatric surgical procedures in patients with a BMI30-35, according to a paper entitled 'Bariatric Surgery for Weight Loss and Glycemic Control in Nonmorbidly Obese Adults With Diabetes A Systematic Review', published in Journal of the American Medical Association.

However, the authors do acknowledge that bariatric surgery does offer short terms benefits such as greater weight loss and better intermediate glucose outcomes, when compared with nonsurgical treatments

"Bariatric surgery for diabetic people who are not severely obese has shown promising results in controlling glucose," said Dr Melinda Maggard-Gibbons, lead author of the study and a surgeon at the David Geffen School of Medicine at UCLA. "However, we need more information about the long-term benefits and risks before recommending bariatric surgery over non-surgical weight-loss treatment for these individuals."

Dr Melinda Maggard-Gibbons


The researchers wanted to assess the association between bariatric surgery vs. nonsurgical treatments, and weight loss and glycaemic control among patients with diabetes or impaired glucose tolerance and BMI 30-35.

After carrying out a literature review (of 1,291 screened articles), they included 32 surgical studies, 11 systematic reviews on nonsurgical treatments, and 11 large nonsurgical studies. Weight loss, metabolic outcomes, and adverse events were abstracted by two independent reviewers.

Three randomised clinical trials found that surgery was associated with greater weight loss (range, 14.4-24 kg) and glycaemic control (range, 0.9-1.43 point improvements in haemoglobin A1c levels) during one to two years of follow-up, than nonsurgical treatment. The improvements were greater in patients treated with gastric bypass than with gastric banding.

Indirect comparisons of evidence from observational studies of bariatric procedures (and meta-analyses of nonsurgical therapies supported this finding at one or two years of follow-up.

However, they could not identify robust surgical data beyond five years of follow-up on outcomes of diabetes, glucose control, or macrovascular and microvascular outcomes.

In contrast, some RCT data of nonsurgical therapies show benefits at ten years of follow-up or more. Surgeon-reported adverse events were low (eg, hospital deaths of 0.3%-1.0%), but data were from select centres and surgeons. Therefore they report that the long-term adverse events are unknown.

"Overall, the [data] all consistently find that weight loss and short-term glucose control are better in patients treated with bariatric surgery," the authors concluded. “Evidence is insufficient to reach conclusions about the appropriate use of bariatric surgery in this population until more data are available about long-term outcomes and complications of surgery.”

 Co-authors of the study were Drs Margaret Maglione, Masha Livhits, Brett Ewing, Alicia Ruelaz Maher, Jianhui Hu, Zhaoping Li and Paul G Shekelle.

The study was funded by the AHRQ and the US Department of Health and Human Services.

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