Monday, October 27, 2014

Bariatric surgery for diabetes: does it work?

- Jennifer Middleton, MD, MPH

I can't remember the last time I referred a patient for weight loss surgery. I precept residents, and I can't remember the last time one of them told me that they'd like to refer their patient for bariatric surgery. I hear colleagues say, not infrequently, that they will not refer patients for bariatric surgery, usually alluding to its risks. Three recently published studies, though, describe the benefits of bariatric surgery to maintain weight loss and potentially reverse co-morbid disease.

The October 15 issue of AFP includes a POEM describing a recent study that compared diabetes outcomes in patients who underwent bariatric surgery compared with those who continued with conventional medication treatment. The study was published in the New England Journal of Medicine in March 2014 and randomized 150 patients with diabetes to either intensive medical management alone or intensive medical management with bariatric surgery (Roux-en-Y bypass or sleeve gastrectomy). Participants had A1Cs > 7.0% (average = 9.3%) at the study onset, had body mass indexes (BMI) that ranged from 27-43, and were between 20 and 60 years old. The researchers studied participants for 3 years and found bariatric surgery + medication superior to medication alone; the number needed to treat (NNT) to get A1Cs less than 6.0% was 3 for Roux-en-Y and 5 for sleeve gastrectomy.

A few months after this NEJM study, Cochrane published a systematic review evaluating the evidence regarding benefits of bariatric surgery. They included all randomized controlled trials (RCTs) comparing either surgery to non-surgical obesity management or different surgical procedures to each other. They looked at several outcomes, including maintenance of weight loss, quality of life, and remission of diabetes. They found that bariatric surgery, overall, "results in greater improvement in weight loss outcomes and weight associated comorbidities compared with non-surgical interventions, regardless of the type of procedures used." They also found, however, that studies did not adequately report complication rates.

Another group of researchers published a slightly different systematic review in the Journal of the American Medical Association (JAMA) a month later. These researchers only included studies whose participants had a BMI of at least 35 and who had at least 2 years of follow-up data, and they did not limit included studies to RCTs. And, although the researchers noted the overall lack of long-term follow-up studies, their findings from the available evidence base to date are in line with the Cochrane reviewers'.

Bariatric surgery is certainly not a zero-risk proposition. But given these outcomes, we should at least be presenting it to appropriate patients as an option among others for obesity and diabetes treatment. The AFP By Topic on Obesity contains further references if you'd like to read more.

How do you discuss bariatric surgery with your patients?