Long-term reduction in body weight and improvement in comorbidities reported for obese adolescents having Roux-en-Y gastric bypass surgery

EBM Focus - Volume 12, Issue 5

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Reference: Lancet Diabetes Endocrinol 2017 Jan 5 early online (level 3 [lacking direct] evidence)

  • Bariatric surgery is recommended for some adolescents with obesity and comorbidity, but information regarding long-term outcomes is lacking.
  • In this uncontrolled study, 58 patients ≤ 21 years old with severe obesity having bariatric surgery were followed for a period of 5-12 years.
  • Persistent weight loss and improvement in comorbidities were observed; however, these were accompanied by micronutrient deficiencies and the need for additional gastrointestinal procedures possibly related to the gastric bypass.

The prevalence of obesity in children and adolescents aged 2-19 years old in the United States is estimated to be 17% (Centers for Disease Control and Prevention). The American Society for Metabolic and Bariatric Surgery Pediatric Committee recommends that bariatric surgery may be considered for adolescents who have reached their adult height and have a body mass index (BMI) ≥ 35 kg/m2 with a serious comorbidity such as type 2 diabetes, or BMI ≥ 40 kg/m2 with a less severe comorbidity such as hypertension. Controlled and uncontrolled studies evaluating bariatric surgery in adolescents suggest favorable effects for weight reduction and remission of comorbidities (JAMA 2010 Feb 10;303(6):519, N Engl J Med 2016 Jan 14;374(2):113, Lancet Diabetes Endocrinol 2017b Jan 5 early online); however, studies reporting on long-term follow-up are lacking. In order to evaluate patients in an extended follow-up, 58 patients (mean age 17 years, 64% female) who had Roux-en-Y gastric bypass surgery in the Follow-up of Adolescent Bariatric Surgery (FABS) study were enrolled in the present FABS-5+ extension study and assessed at a mean of 8 years after surgery. The FABS-5+ study included 81% of eligible patients from the FABS study. The mean baseline BMI of the 14 eligible patients who did not enroll in the FABS-5+ study (64.3 kg/m2) was higher than that of those who did enroll in the study (58.5 kg/m2).

Compared to baseline, there was a 29% reduction in mean BMI from 58.5 kg/m2 to 41.7 kg/m2. At follow-up, 37% had BMI < 35 kg/m2 and 87% had ≥ 10% reduction in BMI. In addition, there was a significant reduction in comorbidities with the rates of hypertension decreasing from 47% to 16% (p = 0.001), dyslipidemia from 86% to 38% (p < 0.0001), and type 2 diabetes from 16% to 2% (p = 0.03). The rates of hypertension and dyslipidemia at follow-up reflect remission in most of the patients, but also new occurrence in some of the patients. Micronutrient deficiencies at follow-up included low levels of iron, vitamin B12 and vitamin D. In addition, 45% had hyperparathyroidism at follow-up. Patients underwent other procedures that may have been related to the gastric bypass surgery including upper endoscopy in 13 patients (22%), cholecystectomy in 12 patients (21%), repair of gastrointestinal perforation in 3 patients (5%), blood transfusion in 2 patients (3%), and exploratory laparoscopy in 2 patients (3%).

In this case series, benefits of bariatric surgery including weight reduction and remission of comorbid conditions persisted for a mean of 8 years after surgery. However, almost two-thirds of patients still had a BMI ≥ 35 kg/m2. The authors report a strong correlation (r = 0.75) between baseline BMI and BMI at long-term follow-up. In addition, there was a significant relationship between BMI at follow-up and risk of dyslipidemia or hypertension. For every 10 kg/m2 higher level of BMI, there was a 34% greater risk of dyslipidemia and a 46% greater risk of hypertension. These data suggest that the baseline BMI may influence the risk of comorbidity after bariatric surgery. It is important to note that the mean baseline BMI of the group of patients who did not enroll in the extension study was higher than those who did. This is a potential source of bias which may have resulted in an overestimation of beneficial effects in this study. Moreover, controlled studies are required to provide more conclusive evidence regarding long-term outcomes. Overall, this study suggests that bariatric surgery in adolescents may provide long-term health benefits in selected obese patients and that careful monitoring for potential nutritional deficits is required. Decisions to perform surgery should weigh the potential necessity for additional gastrointestinal procedures against the expected health benefits.

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