Gastric Bypass Outcomes in Severely Obese Teens

Adolescents with severe obesity who undergo gastric bypass surgery may experience substantial and sustained weight loss, but the procedure is associated with several risks, including vitamin deficiencies and the potential for future surgeries, according to 2 studies published in The Lancet Diabetes & Endocrinology.^1,2

An estimated 4.6 million children in the United States have severe obesity, which is defined as a body mass index (BMI) of 120% or greater of the 95th percentile for age and sex.³

“Bariatric surgery has been used to treat adults with severe obesity for many decades. However, for adolescents, access to surgical care has been limited, in part because long-term evidence of risks, benefits, and durability of weight loss is scant,” Thomas H. Inge, MD, of Cincinnati Children’s Medical Hospital in Ohio, and colleagues wrote.

FABS-5+ Extension Study

In the FABS study (Follow-up of Adolescent Bariatric Surgery; ClinicalTrials.gov identifier: NCT00776776), researchers assessed 1-year outcomes of Roux-en-Y gastric bypass (RYGB) in 74 US adolescents aged 21 years or younger (BMI: 60 kg/m²) between May 2001 and February 2007. In the FABS-5+ extension study,¹ Dr Inge and colleagues sought to extend their follow-up to 5 years.

Of all 74 adolescents who participated in the FABS study, 58 (mean age: 17.1 years) were eligible for FABS-5+. After a mean follow-up of 8 years, average BMI decreased from 58.5 kg/m² at baseline to 41.7 kg/m².

Patients also appeared to experience other improvements in health status after undergoing RYGB. From baseline to follow-up, researchers noted declines in the prevalence of high blood pressure (47% vs 16%; P =.001), dyslipidemia (86% vs 38%; P <.03), and type 2 diabetes (16% vs 2%; P =.03).¹

Despite significant weight loss and improvements in metabolic health, nearly two-thirds of patients remained very obese, with BMIs greater than 35 kg/m².¹

Additionally, several deficiencies were noted at follow-up: 46% of patients had mild anemia, 45% had hyperparathyroidism, and 16% had low amounts of vitamin B12, the researchers reported.¹

“Weight loss is crucial for severely obese patients who face poor health and shorter lifespans,” Dr Inge said in a press release.⁴ “These two manuscripts clearly document long-term benefits of adolescent bariatric treatment, but also highlight several nutritional risks. Now it is important to focus on delivery of the substantial health advantages of surgery while minimizing these risks. Since there are currently 2 effective bariatric procedures, namely gastric bypass and vertical sleeve gastrectomy, we are currently examining the outcomes of both procedures to determine what is best for adolescents.”

AMOS Study

In the AMOS (Adolescent Morbid Obesity Surgery; ClinicalTrials.gov identifier: NCT00289705),⁵ Torsten Olbers, PhD, of the University of Gothenburg and Sahlgrenska Hospital in Sweden, and colleagues compared 5-year outcomes of 81 obese adolescents (mean age: 16.5 years; mean BMI: 45.5 kg/m²) who underwent RYGB with outcomes of 2 control groups: conservatively treated adolescents (n = 80) and adults who also underwent RYGB (n = 81).

After 5 years of follow-up, BMI was reduced by 13.2 points (95% CI, –14.5 to –11.8) in adolescents who underwent RYGB.⁵ Similarly, BMI was reduced by 12.3 kg/m² (95% CI, –13.7 to –10.9). Adolescents who did not have surgery, however, experienced a 3.3-point increase (95% CI, 1.1-4.8) in BMI.⁵

As in the FABS-5+ extension study, metabolic health improved in the adolescent RYGB group. All 3 patients who had type 2 diabetes at baseline were in remission at follow-up.⁵ The prevalence of dyslipidemia also declined from 69% to 15%⁵ and the prevalence of elevated blood pressure declined from 15% at baseline to 0% at 5 years.⁵

During follow-up, 25% of adolescents who underwent RYGB had further surgery to treat complications from the bypass or as a result of rapid weight loss, including bowel blockage and gallstones, and 72% had some type of nutritional deficiency, such as low levels of vitamin D or vitamin B12.⁵