Two of the world’s leading authorities on bariatric and metabolic surgery have issued new evidence-based clinical guidelines for weight loss surgery.

The ASMBS/IFSO Guidelines on Indications for Metabolic and Bariatric Surgery – 2022, published in the journals, Surgery for Obesity and Related Diseases (SOARD) and Obesity Surgery, are meant to replace a consensus statement developed by America’s National Institutes of Health (NIH) more than 30 years ago.

The American Society for Metabolic and Bariatric Surgery (ASMBS) is the largest group of bariatric surgeons and integrated health professionals in the US and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) represents 72 national associations and societies throughout the world.

The guideline include recommendations that expand patient eligibility for weight-loss surgery and endorse metabolic surgery for patients with type 2 diabetes beginning at a body mass index (BMI) of 30.

ASMBS President Teresa LaMasters, MD, said: "The 1991 NIH Consensus Statement on Bariatric Surgery served a valuable purpose for a time, but after more than three decades and hundreds of high-quality studies, including randomized clinical trials, it no longer reflects best practices and lacks relevance to today’s modern-day procedures and population of patients.

“It’s time for a change in thinking and in practice for the sake of patients. It is long overdue.”

In the 1991 consensus statement, bariatric surgery was confined to patients with a BMI of at least 40 or a BMI of 35 or more and at least one obesity-related condition such as hypertension or heart disease.

There were no references to metabolic surgery for diabetes or references to the emerging laparoscopic techniques and procedures that would become mainstay and make weight-loss surgery as safe or safer than common operations including gallbladder surgery, appendectomy, and knee replacement.

The statement also recommended against surgery in children and adolescents even with BMIs over 40 because it had not been sufficiently studied.

The ASMBS/IFSO Guidelines now recommend metabolic and bariatric surgery for individuals with a BMI of 35 or more “regardless of presence, absence, or severity of obesity-related conditions” and that it be considered for people with a BMI 30-34.9 and metabolic disease and in “appropriately selected children and adolescents.”

But even without metabolic disease, the guidelines say weight-loss surgery should be considered starting at BMI 30 for people who do not achieve substantial or durable weight loss or obesity disease-related improvement using nonsurgical methods.

It was also recommended that obesity definitions using standard BMI thresholds be adjusted by population and that Asian individuals consider weight-loss surgery beginning at BMI 27.5.

The new guidelines further state “metabolic and bariatric surgery is currently the most effective evidence-based treatment for obesity across all BMI classes” and that “studies with long-term follow up, published in the decades following the 1991 NIH Consensus Statement, have consistently demonstrated that metabolic and bariatric surgery produces superior weight loss outcomes compared with non-operative treatments.”

It is also noted that multiple studies have shown significant improvement of metabolic disease and a decrease in overall mortality after surgery and that “older surgical operations have been replaced with safer and more effective operations.”

Two laparoscopic procedures, sleeve gastrectomy and Roux-en-Y Gastric Bypass (RYGB), now account for about 90% of all operations performed worldwide.

Roughly one to two per cent of the world’s eligible patient population get weight-loss surgery in any given year.

Experts say the overly restrictive consensus statement from 1991 has contributed to the limited use of such a proven safe and effective treatment.

Globally, more than 650 million adults had obesity in 2016, which is about 13 per cent of the world’s adult population. 

The ASMBS/IFSO Guidelines are the latest in a series of new recommendations from medical groups calling for expanded use of metabolic surgery.

In 2016, 45 professional societies, including the American Diabetes Association (ADA), issued a joint statement that metabolic surgery should be considered for patients with type 2 diabetes and a BMI 30.0–34.9 if hyperglycaemia is inadequately controlled despite optimal treatment with either oral or injectable medications.

This recommendation is also included in the ADA’s “Standards of Medical Care in Diabetes – 2022.”