More than 30 years after the National Institutes of Health developed the initial consensus statement on metabolic and bariatric surgery, two of the world’s leading authorities on these surgeries published new, evidence-based guidelines that expand the scope of indications and potentially chip away at the barriers to these very effective interventions.
The new guidelines, a joint project of the American Society for Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders, reflect the safety of MBS and the evolution of the understanding of the disease of obesity—a profoundly heterogeneous condition that is better treated sooner rather than later (Surg Obes Relat Dis 2022;18[12]:1345-1356).
Barham K. Abu Dayyeh, MD, MPH, a gastroenterologist and an internist with expertise in the endoscopic management of obesity and metabolic diseases, at Mayo Clinic, in Rochester, Minn., said the new guidelines are timely and necessary, especially as the number of people suffering with obesity and obesity-associated diseases continues to grow. “The criteria set 30 years ago [are] not sufficient,” he told Gastroenterology & Endoscopy News. “The prevalence of excess adiposity continues to increase, approaching 50% of the U.S. population being overweight or having obesity. These new guidelines that could increase access to bariatric surgery to a bigger segment of the population are a step in the right direction, and needed in order to get the treatment to patients who need it.”
There were no gastroenterologists/endoscopists involved in the creation of these newest guidelines, but Shanu N. Kothari, MD, a minimally invasive bariatric surgeon at Prisma Health, in Greenville, S.C., and a co-author of the guidelines, said that endoscopic bariatrics is an emerging field and that there have been collaborative guidelines with GI societies about the role of endoscopy in the bariatric patient. “As the technology advances, the lines will continue to blur between what’s extremely minimally invasive surgery and what’s extremely advanced endoscopy,” he said.
Where Does Bariatric Endoscopy Fit?
Octavia Pickett-Blakely, MD, MHS, an associate professor of clinical medicine and the director of GI Nutrition, Celiac Sprue and Obesity Program at Penn Medicine, in Philadelphia, noted that the guidelines include a section on revisional procedures—an area in which endoscopists can help with lifelong management of patients with obesity and metabolic diseases.
“We have the transoral outlet reduction endoscopy that we use in patients whose connection between the stomach and small intestine have stretched over time after Roux-en-Y gastric bypass and experience weight regain. The procedure narrows that connection. For patients who experience regain after gastric bypass surgery, this is a revisional procedure that can help patients lose some of the weight they’ve regained,” Dr. Pickett-Blakely told Gastroenterology & Endoscopy News.
However, she was not surprised that neither endoscopic bariatric procedures nor anti-obesity medications were covered in the guidelines. “That may have been beyond the focus for these guidelines. Also, perhaps the societies are waiting for the body of evidence for bariatric endoscopy to grow further, though in the last 10 years or so we’ve seen a pretty dramatic increase in the body of literature in support of endoscopic procedures for weight loss and metabolic conditions,” she said.
For example, in 2022, the MERIT trial, a multicenter investigation of endoscopic sleeve gastroplasty (ESG), found a mean excess weight loss of 49% in 85 patients who underwent ESG compared with 3% in 124 patients randomized to lifestyle modification alone (Lancet 2022;400[10350]:441-451). Total body weight loss was nearly 14% in the treatment group and less than 1% in the control arm. Obesity-related comorbidities improved in 80% of patients who underwent ESG versus 45% of those who did not. Adverse events related to ESG occurred in three patients (2%); they did not necessitate hospitalization or surgery.
“There’s no question that endoscopic procedures, specifically ESG, are effective for weight loss and also for improvement in metabolic dysfunction,” Dr. Pickett-Blakely said, noting that other modalities, such as duodenal resurfacing and the duodenal-jejunal bypass liner, also have been shown to be effective for metabolic dysfunction and weight loss, although perhaps not as effectively as ESG.
“With the bypass liner, patients lose up to 10% of total body weight. For duodenal mucosal resurfacing, the weight loss results have been less robust, but it’s shown to be quite effective for improvements in insulin resistance, prediabetes and diabetes,” she said.
Dr. Pickett-Blakely observed that while the body of literature supporting endoscopic bariatric procedures continues to accumulate, the field is also attracting specialists trained to provide those services. “The number of endoscopic specialists skilled to do these procedures—a subset of therapeutic endoscopists—is also growing,” she said.
Austin Chiang, MD, MPH, an assistant professor of medicine and the director of the Endoscopic Bariatric Therapy Program at Thomas Jefferson University Hospital, in Philadelphia, said he thinks part of the role of bariatric endoscopy is a matter of patient preference. “Some patients would prefer a potentially reversible option or one that does not result in any external scars. As improvements to technology continue to be made and data emerges to support the efficacy of endoscopic procedures, the benefits of an endoscopic approach may become more pronounced.”
Softening BMI as an Indicator For Intervention
Formerly limited to patients who have a body mass index (BMI) of at least 40 kg/m2, or 35 kg/m2 with the presence of one or more obesity-related comorbidities, the new guidelines support bariatric intervention for patients with a BMI of 35 kg/m2 with or without comorbidities. They also support considering MBS for patients with a BMI of 30 to 35 kg/m2 and a metabolic disease such as type 2 diabetes.
“Millions of patients fall into that category, and we know that the earlier you intervene with MBS, the higher the likelihood of long-term remission of the diabetes. We, too often, see patients after 25 years of type 2 diabetes when they have significant end-organ damage, are at the highest perioperative risk for surgical complications and the lowest chance that the surgery will have a successful impact on their diabetes,” Dr. Kothari noted.
In addition, the guidelines suggest that BMI thresholds should be adjusted in Asian populations based on the understanding that these patients tend to experience worse disease. The paper establishes a BMI of 25 kg/m2 for clinical obesity in Asian patients and recommends offering MBS to those in this population with a BMI of 27.5 kg/m2 or higher.
“We know now that diabetes and hypertension are different diseases in the Asian population. They come on at a lower BMI and are more severe. Based on the 1991 NIH guidelines, these populations were being discriminated against by adhering to the previously determined BMI units,” Dr. Kothari said.
From Pediatric to Geriatric Populations
Acknowledging that patient selection is critical in older patients, the guidelines state that there is no known upper chronological age limit for MBS. In older patients, the slightly higher risk for surgical complications should be weighed against the benefits of weight loss and remission of obesity-related comorbidities.
At the other end of the spectrum, the guidelines recognize that MBS is safe for patients under 18 years of age and has the potential benefit of sparing a patient years or decades of the burden of obesity and its associated comorbidities. They recommend considering MBS for children and adolescents who have a BMI greater than 120% of the 95th percentile class in the presence of a major comorbidity, or 140% of the 95th percentile without a comorbidity.
Bridging and High-Risk Patients
MBS also can be considered for patients who may need to undergo joint replacement, organ transplantation or abdominal wall hernia repair, whose outcomes would likely be superior if they are able to undergo weight loss first, or who might never make it to surgery without weight loss.
“This is an area where we can help other subspecialty societies in all those respective disciplines. If a patient undergoes MBS and can lose 100 pounds before a hip or knee replacement, we know we lower the operative time for joint arthroplasty and decrease the risk of perioperative complications,” Dr. Kothari said.
The guidelines also suggest that MBS should not be withheld from high-risk patients, such as those with a BMI greater than 60 kg/m2 and those who have cirrhosis or heart failure. As with all the other expanded indications, this recommendation comes in part from the well-established safety of MBS.
“I think a lot of people have the misunderstanding that bariatric surgery should be reserved for the worst of the worst, and that’s not true. The BMI guidelines are lower because the safety of surgery has dramatically improved in the last 30 years—a quality success story,” said Teresa LaMasters, MD, the medical director of the UnityPoint Clinic Weight Loss Specialists in West Des Moines, Iowa, and current president of the ASMBS. “Part of this is the system of care we have around patients: our preoperative preparation and optimization, plus the multidisciplinary approach to patients both pre- and post-surgery. This is how we do very high-risk patients very safely.”
The Next Stage
Most certainly it will not be another 30 years before the guidelines are revised, Dr. LaMasters said—more likely within the next five years, which will allow time for an adequate volume of research and literature to evolve.
Dr. Abu Dayyeh said he would welcome future collaboration. “Collective wisdom is important to move the field forward. We need collaboration that involves surgeons, gastroenterologists, endocrinologists, nutritionists and psychologists to address the disease of obesity.
“Bariatric surgery is, in my opinion, a lifesaving intervention. But we have not broken past that 1% to 2% of eligible patients receiving MBS because of the barriers of cost and invasiveness. I think the spectrum of effective therapeutics is going to continue to expand to include anatomy-sparing interventions that work along the same pathway as bariatric surgery and can reach more patients.”
—Monica J. Smith
Dr. Abu Dayyeh reported financial relationships with Apollo Endosurgery, Boston Scientific, Endogenex, Medtronic, Spatz Medical and USGI Medical. Dr. Chiang is employed by Medtronic. Drs. Kothari, LaMasters and Pickett-Blakely reported no relevant financial disclosures. Dr. Chiang is a member of the Gastroenterology & Endoscopy News editorial board.
This article is from the April 2023 print issue.