Very Obese Teens: Promote or Postpone Gastric Bypass?

Severely obese adolescents and adults who weighed on average 147 kg (324 pounds) were about 38 kg (84 pounds) lighter 5 years after they had bariatric surgery — and the adolescents were more likely to have remission of diabetes and hypertension, a new study reveals.

On the other hand, the adolescents were also more likely to have iron deficiency, need an abdominal reoperation, or die by drug overdose (although this was very rare).

Therefore, whether a very obese teen should have gastric bypass surgery while still an adolescent or postpone until later depends on the individual patient, says one expert.

Results Published for Childhood Obesity Summit in Houston

The new findings, by Thomas H. Inge, MD, PhD, University of Colorado, Denver, and Children's Hospital, Aurora, and colleagues, are based on a comparison of outcomes after Roux-en-Y gastric bypass in teens in the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study versus adults in the LABS study.

"We have documented similar and durable weight loss after gastric bypass in adolescents and adults, but important differences between these cohorts were observed in specific health outcomes," they summarize in their article article published online May 16 in the New England Journal of Medicine to coincide with the Combating Childhood Obesity summit in Houston, Texas.

In this study, and a similar one by Olbers and colleagues (Lancet Diabetes Endocrinol. 2017;5:174-183), "the 5-year data [for gastric bypass in very obese teens] look promising but...the lifetime outcome is unknown," cautions Ted D. Adams, PhD, MPH, Intermountain Healthcare and University of Utah, Salt Lake City, in an accompanying editorial.

Inge and colleagues agree that "longer-term follow-up and further research will be important for refinement of the risks and benefits of bariatric surgery in adolescents."

In the meantime, Adams advises, "the decision whether to recommend bariatric surgery treatment for adolescents with severe obesity or to postpone the surgery to adulthood...[needs to be] made after careful consideration of related harms and benefits."

Adolescents may not to be capable of making an informed decision about weight-loss surgery, he notes.

"For now," Adams concludes, "while we hope to identify new, effective, and less invasive therapies and effective adjuncts to bariatric surgery in adolescents (ie, pharmacotherapy and multispecialty lifestyle integration), decisions should be made on a case-by-case basis."

Adolescents More Likely to Have Remission of Diabetes, Hypertension

Bariatric surgery, which is effective for treating severe obesity in adults, is most often performed in patients in their 30s or 40s, the authors explain.

But it is not clear if severely obese adolescents should have this surgery or wait until they are older.

This issue is becoming increasingly important, Adams writes, because almost 6% of adolescents in the United States are severely obese (body mass index [BMI] ≥ 35 kg/m²).

To investigate this, researchers identified 161 severely obese adolescents in the Teen-LABS study who were 13 to 19 years old (mean age 17) when they had Roux-en-Y gastric bypass at five centers in 2006-2012.

They compared this cohort with 396 severely obese adults in LABS who had been obese at age 18 and had a gastric bypass at age 25-50 (mean age, 38) at 10 centers in 2006-2009.

Participants in both groups had a mean BMI of 50 kg/m² when they had the bariatric surgery and 77% were female.

Five years after surgery, the adolescents and adults had lost a similar amount of their initial weight, 26% and 29%, respectively (P = .08).

However, the rate of diabetes dropped more among adolescents than adults (from 14% to 2.4% vs from 31% to 12%).

Similarly, the prevalence of hypertension declined more among adolescents than adults (from 30% to 15% vs from 61% to 39%).

So compared to adults, adolescents were significantly more likely to have remission of diabetes (86% vs 53%; risk ratio, 1.27) and hypertension (68% vs 41%; risk ratio, 1.51).

Rare but Worrisome Drug Overdoses

The mortality rate during the 5-year follow-up was similar in both groups — three adolescents (1.9%) and seven adults (1.8%) died — but the causes differed.

The teens died from drug overdose (two patients) and sepsis following hypoglycemia (one patient with type 1 diabetes).

The adults died from gastric bypass-related causes (three patients), indeterminant causes (two), suicide (one), and colon cancer (one).

"Although the 5-year rates of death were similar in the two groups," Adams writes, "it is troubling that the cause of death in two of the three adolescents [who died] was consistent with overdose."

This is a "worrisome" finding, Inge and colleagues agree, "given the overall increasing trend of drug overdose deaths in the United States, and in light of the increased risk of substance- and alcohol-use disorders reported in adults after gastric bypass surgery."

"Indeed," they continue, "despite the small numbers of persons thus far affected by overdose after gastric bypass surgery, these findings may indicate a need for more focused research efforts, patient education, and anticipatory guidance."

In addition, although presurgery ferritin levels were normal in 98% of adolescents and adults, by 2 years after the surgery significantly more adolescents than adults had low ferritin levels (48% vs 29%; P = .004).

Moreover, during the 5-year follow-up, more adolescents than adults had intra-abdominal operations (20% vs 16%), which were mainly cholecystectomy, and less frequently surgery for bowel obstruction, hernia repair, or gastrostomy.

The ongoing Teen-LABS study has recently begun enrolling teens undergoing sleeve gastrectomy.

The Teen-LABS consortium is supported by the National Institute of Diabetes and Digestive and Kidney Diseases. The authors have reported no relevant financial relationships.

N Engl J Med. Published online May 16, 2019. Abstract, Editorial

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