New studies show bariatric surgery can improve health for patients with Class 1 obesity

Patient eligibility for bariatric surgery, also called weight-loss or metabolic surgery, has expanded over the last decade and its safety and effectiveness even further established in clinical studies and professional guidelines, but relatively few patients with a body mass index (BMI) below 35 actually get the surgery in any given year, according to new studies presented here at the American Society for Metabolic and Bariatric Surgery (ASMBS) 2023 Annual Scientific Meeting.

In one study, University of Southern California (USC) researchers found only 3.5% of the more than one million bariatric surgery procedures performed between 2015 and 2021 were on patients with a body mass index (BMI) of 30 to 35, classified as Class 1 obesity. This amounts to little more than 38,000 patients who had similar improvements in health status and underlying metabolic disorders and the same low rates of complications (less than 5%) and mortality (less than 0.1%) as their higher BMI counterparts. Sleeve gastrectomy was the most common procedure for both patient groups.

Data was obtained from the Metabolic Bariatric Surgery Accreditation Quality Improvement Program (MBSAQIP), which maintains a database of inpatient and outpatient bariatric surgery procedures performed in accredited centers throughout the U.S. and Canada.

Despite widespread acceptance of bariatric surgery as the most effective treatment for obesity, significant barriers to treatment still exist across the spectrum of obesity and in particular, those on the lower end. Generally, the earlier the intervention on obesity or any disease, the better the outcome. Patients need not wait until their obesity and related conditions become severe before seeking bariatric surgery."

Paul Wisniowski, MD, study co-author, surgical resident at USC

In a new IRB registry study, of 30 patients with BMI 30 to 35 who underwent bariatric surgery at Overlook Medical Center between 2017 and 2021, researchers from New Jersey Bariatric Center found nearly 60% lost at least half their excess body weight and 56.25% saw improvements or resolution of an obesity-related disease such as type 2 diabetes or hypertension. None of the patients experienced complications.

"Our study shows significant weight loss and health benefits, as well as the safety and efficacy of the gastric bypass and gastric sleeve procedures, for this patient population," said Ajay Goyal, MD, principal investigator and bariatric surgeon at New Jersey Bariatric Center. "Often by the time a patient qualifies for bariatric surgery their weight-related medical conditions such as diabetes and hypertension are severe. By expanding access to bariatric surgery to patients with a lower BMI with obesity-related illnesses, patients can halt the progression, and in some cases resolve, significant and uncontrolled weight-related chronic diseases through weight loss."

In 2018, the ASMBS updated its position on Class 1 obesity stating "bariatric surgery should be offered as an option" and access "should not be denied solely based on this outdated threshold", referring to the prior minimum BMI requirement of 35. It further notes that current nonsurgical treatments "are often ineffective at achieving major, long-term weight reduction and resolution of co-morbidities."

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

"Professional guidelines and increasing data support bariatric surgery for patients beginning at BMI 30, which is a tipping point for disease progression. Now it needs to happen in the real world," said Teresa LaMasters, MD, President, ASMBS and a bariatric surgeon and board-certified obesity medicine physician, who was not involved with the studies. "We encourage greater consideration of this important treatment option earlier in the disease process."

In 2022, ASMBS and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) representing 72 national associations and societies throughout the world, issued new evidence-based clinical guidelines that among a slew of recommendations expanded patient eligibility for weight-loss surgery and endorsed metabolic surgery for patients with type 2 diabetes beginning at a body mass index (BMI) of 30.

The ASMBS reports only about 1% of those who meet eligibility requirements get weight-loss surgery in any given year. In 2020, the number of bariatric procedures dropped to less than 200,000, the lowest in four years, due to cancellations or deferrals during the height of the COVID-19 pandemic. Procedures appeared to have rebounded in 2021, but official estimates are not yet available.

According to the U.S. Centers for Disease Control and Prevention (CDC), obesity effects 42.4% of Americans. Studies show the disease can weaken or impair the body's immune system and cause chronic inflammation and increase the risk of many other diseases and conditions including cardiovascular disease, stroke, type 2 diabetes, certain cancers, and COVID-19.