New Indications for Bariatric Surgery: My Reservations

Neil Skolnik, MD


December 08, 2022

This transcript has been edited for clarity.

I'm Dr Neil Skolnik, and today we are going to talk about the American Society for Metabolic and Bariatric Surgery (ASMBS) "Indications for Metabolic and Bariatric Surgery." These are the first new guidelines to address this issue since the National Institutes of Health (NIH) consensus statement in 1991, so this is a much-needed update. I'm going share these new guidelines and give you my opinion.

For 30 years, the NIH consensus statement has set the standard selection criteria for metabolic and bariatric surgery (MBS) at a BMI 40 or BMI 35 with comorbidities.

Over time, bariatric surgery has become safer, and we have accumulated a lot of evidence showing its benefits. With regard to safety, perioperative mortality is now very low, ranging between 0.03% and 0.2%. Currently, the dominant procedures are sleeve gastrectomy and Roux-en-Y gastric bypass, usually performed though minimally invasive surgery — either laparoscopic or robotic assisted.

Weight loss from bariatric surgery is in the range of 60% of excess body weight, varying, of course, depending upon the procedure, with durability of weight loss for 5-20 years.

It's not just the effect on weight though that is important. Compared with nonsurgical control patients, studies have shown improvement in type 2 diabetes, hypertension, and dyslipidemia beyond 10 years as well as lower risk for new-onset heart failure, myocardial infarction, and stroke, and for people with class II/III obesity, even cancer. Finally, large studies have shown lower mortality over time. The Swedish Obese Subjects study demonstrated an adjusted overall mortality decline of approximately 30% in the group of more than 2000 surgical patients compared with nonsurgical controls, at an average of 10 years after surgery.

This all leads to the following updated criteria for surgery:

  • Class I obesity (BMI 30-34.9): Bariatric surgery should be considered a treatment option for patients with class I obesity who do not achieve substantial or durable weight loss or comorbidity improvement with nonsurgical methods. It is recommended that a trial of nonsurgical therapy is attempted before considering surgical treatment.

  • MBS is recommended in patients with type 2 diabetes and BMI ≥ 30.

  • Class 2 obesity (BMI ≥ 35): The guidelines say that metabolic and bariatric surgery should be strongly recommended in these patients regardless of obesity-related comorbidities.

  • In the Asian population, the prevalence of diabetes and cardiovascular disease is higher at a lower BMI than in the non-Asian population. So the BMI risk zones should be adjusted to define obesity at a BMI threshold of 25-27.5 in this population.

Now, I'll share my opinion. These guidelines are long overdue. A recommendation that metabolic and bariatric surgery should be considered for "suitable individuals with class I obesity" (a BMI of 30-35 with comorbidities who have not had an adequate response to nonsurgical therapy) makes a lot of sense. It's an important option, and at this point, is safe and has a good evidence base for efficacy.

However, the statement that bariatric surgery should be "strongly recommended" to patients with a BMI ≥ 35 regardless of obesity-related comorbidities is something that I am concerned about and frankly don't agree with. That recommendation does not take into account the incredible efficacy of current weight loss medications, specifically glucagon-like peptide 1 (GLP-1) receptor agonists, and, moving forward, does not take into account other weight loss medications that already have published phase 3 trials, specifically GLP-1/gastric inhibitory polypeptide (GIP) dual-agonists (not yet US Food and Drug Administration (FDA) approved, but phase 3 trials have been completed).

These medicines reliably achieve an average of 15%-22% weight loss with improvements in metabolic parameters. Most importantly, the guidelines also do not address patient values and preferences, which is important to acknowledge because not every patient wants to undergo surgery. For all patients, and certainly those with a BMI ≥ 35, a discussion of options and shared decision making are, in my opinion, the optimal approach.

For people with diabetes and obesity, I prefer the recommendation of the American Diabetes Association, which says, "Metabolic surgery may be considered as an option to treat type 2 diabetes in adults with a BMI 30-34.9 who do not achieve durable weight loss and improvement in comorbidities including hyperglycemia with nonsurgical methods."

Finally, I have to say, while we are on the topic, it's critical to address primary prevention with patients and provide recommendations for healthy eating and physical activity.

I'm interested in your thoughts, please leave them in the comments section.

This is a critically important update for something that we advise patients on every day.

I'm Neil Skolnik, and this is Medscape.

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