A Cochrane review109 identified ten randomised controlled trials of pharmacological treatments for obese children.
Most of these trials had small sample sizes (range 24-539 participants, with 60% including fewer than 30 participants), but most were high quality. With one exception, all the pharmacological treatment trials were in older children or adolescents (minimum age 12 years); the exception enrolled individuals aged 9-18 years. Trials meeting criteria for pooled meta-analysis included only two drugs: orlistat (a lipase inhibitor that prevents absorption of dietary fat from the gut) and sibutramine (an inhibitor of serotonin, norepinephrine, and dopamine reuptake).
The additional effect of orlistat compared with placebo when given in combination with a lifestyle intervention was a difference in BMI of -0·76 kg/m2 (95% CI -1·07 to -0·44) at 6 months. The additional effect of sibutramine compared with placebo when given in combination with a lifestyle intervention was a difference in BMI of -1·66 kg/m2 (95% CI -1·89 to -1·43) at 6 months. For long-term outcomes, there has been only one randomised trial of orlistat, which showed a change in BMI of -0·55 kg/m2 with orlistat versus 0·31 kg/m2 with placebo at 12 months (p=0·001),136 and only one randomised trial of sibutramine, in which investigators reported a change in BMI of -2·9 kg/m2 with sibutramine versus -0·3 kg/m2 with placebo at 12 months (p<0·001).137
Side-effects (reported as prevalence in excess of that reported for placebo) of orlistat were oily stool (42%), abdominal pain (11%), faecal incontinence (9%), and new cholelithiasis (2%).136 Side-effects of sibutramine were tachycardia (6%), dry mouth (5%), constipation (4%), dizziness (4%), insomnia (3%), and hypertension (2%).137 Thus, although evidence exists for slight effectiveness of orlistat and sibutramine when combined with lifestyle intervention, treatment with these drugs is associated with more adverse effects than is lifestyle intervention alone.
No randomised controlled trials of bariatric surgery have been done in children or adolescents.109 In a systematic review of observational studies reporting outcome data in patients aged 21 years or younger (range 9-21 years, mean 16·8 years) with a minimum follow-up of 12 months, investigators identified four studies of Roux-en-Y gastric bypass (a restrictive and malabsorptive procedure)138 and six of laparoscopic adjustable gastric banding (LAGB; a purely restrictive procedure) that met inclusion criteria for meta-analysis (figure 4).139
For gastric bypass, the 95% CI for change in BMI from baseline was -17·8 to -22·3 kg/m2 at 1-6·3 years, and for gastric banding, -13·7 to -10·6 kg/m2 at 1-3 years.139 Complications of gastric bypass were pulmonary embolism, shock, intestinal obstruction, postoperative bleeding, staple-line leak, and severe malnutrition;139 those of gastric banding were band slippage or erosion, micronutrient deficiency, port or tube dysfunction, hiatal hernia, wound infection, and pouch dilatation.139 Long-term prospective studies are needed to establish safety and efficacy of restrictive and malabsorptive procedures and to establish whether reductions in morbidity and mortality outweigh the risks of serious surgical complications and life-long nutritional deficiencies.
Large trials that are suficiently powered to examine long-term effects and that allow direct comparisons of non-pharmacological, pharmacological, and surgical treatments are needed. In view of the paucity of data, poor effectiveness, and unknown risks for long-term drug use, we recommend a conservative approachnamely, to use pharmacotherapy only in patients with BMI higher than the 95th percentile who have substantial medical complications of obesity and after a reasonable period of behavioural intervention. The risks of bariatric surgery are substantial, and long-term safety and effectiveness in children remain largely unknown.
Therefore, surgery should be reserved for only the most severely obese (BMI ≥50 kg/m2, or ≥40 kg/m2 with important comorbidities), and even then, considered with extreme caution.
Much progress has been made in understanding of the genetics and physiology of appetite control and, from this, the elucidation of the causes of some very rare obesity syndromes. Much work remains to be done, however, since these rare disorders have so far taught us few lessons about how to prevent or reverse obesity in most children. No evidence-based, clinically meaningful definition of childhood obesity has been established.
Calorie intake and activity recommendations need to be reassessed and better quantified at a population level because of the modern sedentary lifestyles of children.