Bariatric Surgery Before Age 18 May Have Lifelong Benefits

October 1, 2012 (San Antonio, Texas) — Bariatric surgery in teenagers might avert a number of metabolic problems in later life, according to a retrospective study of obese adults that endeavored to model how their health might have been different had they had bariatric surgery at age 18.

Nationally, 7% of 18-year-olds meet the definition of extreme obesity, and that number is growing every year, according to pediatric surgeon Thomas Inge, MD, PhD, from the Cincinnati Children's Hospital Medical Center in Ohio.

"When we looked at children in the Princeton School District cohort" over 5 years, excluding those with a body mass index (BMI) over 40 kg/m², "they continued to gain weight and they gained at a rate of 1 BMI point a year thereafter," Dr. Inge told Medscape Medical News.

Dr. Inge also showed data hinting that diabetes in adolescence might be "more virulent," he said. "If that's the case, shouldn't we think of more aggressive therapies" earlier on?

In their study, Dr. Inge and colleagues looked retrospectively at 1492 morbidly obese adults who were seeking bariatric surgery to determine if their comorbidities later in life could be associated with their body weight when they were teenagers. Dr. Inge presented the results here at Obesity 2012: The Obesity Society 30th Annual Scientific Meeting.

The median age of the study subjects was 47 years. The median adult BMI was 46 kg/m², whereas median age 18 BMI, based on participant recollection, had been 26 kg/m². In multivariate analyses, weight status at age 18 emerged as a key predictor of adult disease, including renal disease, diabetes, hypertension, and venous stasis, he said.

Adolescent Weight Status as Predictor of Future Disease

Future Disease	Adjusted Relative Risk
Renal disease	5.82
Diabetes	1.37
Hypertension	1.23
Venous stasis	6.39
Walking limitation*	4.34
Asthma	1.47

*defined as the ability to walk 200 feet without assistance

"The critical point is that after 18, you may be past the point of no return," said Dr. Inge. "The die is cast, so to speak, for developing diabetes, metabolic syndrome, and hypertension."

Dr. Inge continued: "One of my messages is that if we can operate on teenagers at a critical time, when they have severe insulin resistance but do not yet have diabetes, my prediction is that we'll cut down on these other things developing.

"There's good evidence that even if you remedy that insulin resistance for only a short period, you can have decades-long better outcomes from it, likely because of metabolic memory," Dr. Inge said. "Even if they regain weight later in life, there may be a benefit from having normalized their insulin resistance and metabolic status during their adolescence."

He cited earlier work by his group looking at 11 adolescents with BMIs greater than 50 kg/m² who, in the year after undergoing bariatric surgery, dropped their BMIs to 33 kg/m², reduced their diabetes medication use, and significantly lowered their triglyceride, total cholesterol, low-density lipoprotein, and glycated hemoglobin levels.

Another earlier study of 23 adolescents with "enormous BMIs, greater than 60," showed impressive drops in BMI, as well as normalization toward the mean of their insulin resistance.

Fundamental Metabolic Change

"I think these operations are doing something fundamentally metabolic to improve the patients' response to whatever the pathological diabetes milieu is," Dr. Inge said. "We don't know exactly why, but it's fairly clear this is metabolic surgery."

He continued: "When we study people who have, without surgery, lost 20% to 30% of the weight, their bodies turn off some autonomic nervous functions to get their weight back up. So the body thinks it's under attack and regains the weight. The big mystery is how surgery tricks it. Bypass surgery, unlike any drug or behavioral therapy, somehow alters the set point where the hypothalamus thinks it wants the body to be."

Commenting on the study, Christy Turer, MD, from the University of Texas Southwestern Medical Center in Dallas, expressed the hesitation that other pediatricians have about pediatric weight loss surgery: It's permanent.

"I absolutely agree that surgical weight loss improves diabetes parameters," she told Medscape Medical News, "but I'm still concerned about the longer-term impact over a lifetime of intervening on kids in a fashion that in many cases is irreversible. I'm thinking of the impact on their bones, on their psyches, and whether they will have a need for reoperation."

Christine Roberts PhD, MBA, coordinator of the CARE program at the Phoenix Children's Hospital in Arizona, is considering initiating a surgical weight loss program for teenagers at her medical center. "We don't have any pediatric bariatric programs in Arizona," she said.

However, she has concerns. "You have to be very specific in who you do it in. The results are indeed positive, but there's a lot of follow-up. These are kids. The expectation is that they're going to live another 60, 70 years, but we don't know what's going to happen when they're 50, 60, 70. I think if you can reduce their comorbidities, they may be able to get to those ages, because right now these kids may not make it past 40 or 50."

Potential Long-term Effects

She also mentioned the potential long-term psychological effects and how these relate to the psychological causes of being overweight in the first place. "That's the difference between adolescents and adults. Adults are in charge of their own reasons for being where they're at, but adolescents may not be."

Finally, Suzanne Cuda, MD, from the Pediatric Weight Management Center at the US Air Force in San Antonio, Texas, noted that 70% of the teenaged patients who present at her center are above the 99th percentile for weight. "We have a lot of patients who, despite intensive treatments, are still not making enough progress toward achieving lower BMIs and continue to develop comorbidities.

"It's an ethical dilemma when you have a teenaged patient who's not doing well and there's a procedure that may help them, Dr. Cuda said. "But it's controversial. We don't have long-term data. What happens to a 16-year-old 15 years from now? We don't know."

Dr. Inge told Medscape Medical News about a robust long-term outcome study his group is conducting that contains a registry of childhood obesity cases that will be open to other researchers.

"We're recruiting participants in our 5-center consortium for our Teen-LABS [Teen-Longitudinal Assessment of Bariatric Surgery] study, mostly gastric bypass cases. We're also looking for scientists who want to gather data within our cohort. We collect plasma, serum, fat tissue, and urine. We're also studying special populations of kids, such as adolescents with sleep apnea, to see what happens over years."

Currently, Dr. Inge and colleagues are collecting cases and starting to come up with research topics using the database. "With gastric surgery, I'm convinced that metabolic defects can improve. And I think that surgical models, whether they are bypass or sleeve gastrectomy or other surgical models that may be out there on the horizon, hopefully will provide mechanisms we can exploit to put more tools in our toolbox."

Dr. Inge's work is funded by the National Institutes of Health. The Cincinnati Children's Hospital Medical Center receives funding on his behalf from Ethicon Endosurgery for another long-term follow-up study he is conducting. Dr. Turer, Dr. Roberts, and Dr. Cuda report no relevant financial relationships.

Obesity 2012: The Obesity Society 30th Annual Scientific Meeting. Presented September 21, 2012.