Classifying Patients with Obesity to Predict Bariatric Surgery Outcomes

Researchers classified individuals into four subtypes of obesity to assess who might achieve sustained weight loss after gastric bypass surgery.

With Anita Courcoulas, MD, and J. Michael Gonzalez-Campoy, MD, PhD

Patients want some assurance that having gastric bypass surgery will be beneficial so they can feel better about making the decision to move ahead. However, having the ability to more closely predict which patients with obesity will achieve desired outcomes following bariatric surgery has posed an ongoing challenge for physicians.

Now there is a useful roadmap based on patient characteristics to guide clinicians in recommending who may be most likely to experience favorable results,1 using findings published in the journal, Obesity.

Obesity patients with disordered eating lost more weight after bariatric surgery.

Bariatric Surgery: Do Some Patients with Obesity Benefit More?

The authors reported that patients undergoing gastric bypass who were diagnosed as having disordered eating achieved the greatest sustained weight loss, in comparison to patients grouped in three other obesity subtypes.1

"Patients with disordered eating behaviors benefited more from bariatric surgery than patients with diabetes and/or those with early onset of extreme obesity," said lead author, Anita Courcoulas, MD, chief of the section of minimally invasive bariatric and general surgery at the University of Pittsburgh School of Medicine.

"It appears from the data that people classified as having disordered eating responded with somewhat better weight loss at the three-year post-surgery timepoint," Dr. Courcoulas told EndocrineWeb.

Classifying Bariatric Surgery Candidates by Subtype

The Pittsburgh Medical School researchers conducted an analysis of 2,458 adults enrolled in the Longitudinal Assessment of Bariatric Surgery (LABS) study, to look for any trends in weight change achieved after three years of follow-up in patients who underwent bariatric surgery.1

The researchers identified patients into four obesity subtypes, as follows:

  • Subtype 1: Diabetes with low rates of high-density lipoprotein  
  • Subtype 2: Disordered eating  
  • Subtype 3: Mixed
  • Subtype 4: Early onset extreme obesity  

About 98% of patients in the subtype 1 group had diabetes whereas less than 40% of those in the other classes had this chronic disease. Individuals who were classified with disordered eating, subtype 2, had high rates of binge eating. The patients with higher body mass index (morbid obesity) at baseline comprised subgroup 4, of which most also had a history of early-in-life weight gain.1

To receive the classification of binge eating disorder, these patients had to report at least once weekly episodes of binging, coupled with feeling a loss of control during the episode(s), Dr. Courcoulas said.

Characteristics of Participating Patients with Obesity

The patients from the LABS study had undergone gastric bypass surgery at one of 10 hospitals in geographically diverse centers—New York, Pennsylvania, Seattle, Fargo, Greenville, and Portland, between March 2006 and April 2009.2

In all, the researchers analyzed 2,456 records.1 As part of their treatment plan, the participants agreed to attend post-surgery follow-up visits for a duration of seven years, at their designated center at:

  • 30 days
  • 6 months
  • one year
  • annually (in years 2-7)

The researchers used a broad range of psychological, behavioral, and biological parameters, including data on appetitive behaviors, disordered eating, family history of obesity and markers of cardiometabolic health to identify subtypes of obesity. They then placed the patients into one of four classifications.

As might be expected, most people fit into the mixed class, with 1,108 patients falling into this subgroup. There were 365 patients in the early onset/high BMI subgroup, 892 patients fell into the disordered eating subgroup, and interestingly, only 91 individuals met the criteria for the diabetes subgroup.1

Patients with Disorder Eating Responded Best 

At the three-year mark, the patients classified as subtype 2 with disordered eating achieved the most weight loss. "Patient with disordered eating behaviors benefited more from bariatric surgery than the patients with diabetes and/or patients with early onset extreme obesity," Dr. Courcoulas said.

"Both men and women with disordered eating lost the most weight compared to other groups, with an average BMI decline of 28.5% and 33.3%, respectively, from their presurgery weight."

When asked for the reason behind the greater success in this subgroup, she offered the following explanation: "I would hypothesize that this may be due to the fact that the surgery helps to control portion size, appetite, and some other contributing factors."

Those in subgroup 4, with early onset obesity, lost 25% (men) and 30% (women) of their starting weight, which was closely matched those in subgroup 1: patients with diabetes and low HDL.1  The majority of individuals, who were in the mixed obesity subgroup 3, lost 28% (men) and nearly 32% (women) of their initial BMI.

However, as even Dr. Courcoulas said, it would be important to follow these people even longer because other studies have reported that people with disordered eating are more likely to experience weight regain than those without this characteristic.

Regardless—Patients with Obesity Benefit from Surgery

Findings from this study ''highlights that not all patients who have overweight or obesity have the same biology and it appropriately calls for focusing on bariatric surgery interventions to patients who are at the highest health risk," says J. Michael Gonzalez-Campoy, MD, PhD, FACE, medical director and CEO of the Minnesota Center for Obesity, Metabolism and Endocrinology in Evans, Minnesota.

Dr. Gonzalez-Campoy told EndocrineWeb, in his opinion, "patients who have adiposity (eg, increased fat mass resulting in physical complications) will have improvement in their health with bariatric surgery-induced weight loss. Patients who have adiposity and adiposopathy (eg, adipose tissue dysfunction contributing to metabolic derangements, including diabetes) will benefit more."

The paper reinforces the chronic nature of obesity. "Overweight, obesity and adiposopathy are life-long diseases, and this study provides only three years of observation immediately following bariatric surgery,” he said.

“The short-term success of bariatric surgery in reducing overweight and treating adiposity and Adiposopathy—thereby returning adipose tissue to normal function, and improving metabolic diseases—may not be easily sustained over longer periods of time,” said Dr. Gonzalez-Campoy. 

“As such, this paper underscores the importance of addressing any other issues that may counter the success of the surgery alone, such as an eating disorder or diabetes,'' he said, and surgery or not, ''all these patients have a life-long disease, so ongoing pharmacotherapy for weight loss is appropriate, likely for the long-term. And monitoring these patients for complications of obesity and malabsorption from the surgery will also require life-long monitoring.''

Predicting Obesity Surgery Success: Other Take-Home Points

"This was one of the first studies to examine psychological variables, such as eating patterns, weight history, and a range of biological variables, including hormone levels, to identify different types of obesity in people undergoing bariatric/weight loss surgery,'' Dr. Courcoulas told EndocrineWeb.

“The study highlights the heterogeneity in response to obesity treatments, including bariatric surgery ''and understanding that heterogeneity will help to better target the right treatment of the right patients," said Dr. Courcoulas.

This potential for classifying patients with obesity into predictive subgroups needs further research, she said, but the differences they were able to tease out offer a good start in working with this diverse group of patients and may have important implications for more accurately targeting obesity treatment going forward.

"We expect this work will help to better target treatments to specific groups of people who may be more (or less) likely to respond as desired to gastric bypass surgery."

Dr. Courcoulas reports research grants from Covidien and Ethicon J&J Healthcare. Dr. Gonzalez-Campoy has no financial conflicts.

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