A Cochrane review (abstract , review ) included 64 studies with a total of 5 230 patients. Lifestyle interventions focused on physical activity and sedentary behaviour in 12 studies, diet in 6 studies, and 36 concentrated on behaviorally orientated treatment programs. Three types of drug interventions (metformin, orlistat and sibutramine) were found in 10 studies. All drug studies were performed in adolescents. No surgical intervention was eligible for inclusion.
Lifestyle interventions reduced overweight at 6 months (MD in BMI-SDS –0.06, 95% CI –0.12 to –0.01; 4 studies, n=301) and 12 months follow up (MD in BMI-SDS –0.04, 95% CI –0.12 to 0.04; 3 studies, n=264) in studies involving children under 12 years and also in studies involving children 12 years and older (6 months follow up: MD in BMI-SDS -0.14, 95% CI -0.17 to -0.12; 3 studies, n=291; MD in BMI -3.04, 95% CI -3.14 to -2.94; 4 studies, n=362; 12 months follow up: MD in BMI-SDS -0.14, 95% CI -0.18 to -0.10; 2 studies, n=231; MD in BMI -3.27, 95% CI -3.38 to -3.17; 2 studies, n=231).
Pooled meta-analysis found an additional effect of orlistat (MD in BMI -0.76, 95% CI -1.07 to -0.44; 2 studies, n=579) and sibutramine (MD in BMI -1.66, 95% CI -1.89 to -1.43; 2 studies, n=111) over placebo on absolute BMI at 6 months follow up, when given in combination with a lifestyle intervention. A range of adverse effects was noted in drug studies.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment, unclear blinding, and more than 20% loss to follow up) and by inconsistency (heterogeneity in interventions and outcomes).
Clinical comment: Sibutramine has been associated with increased cardiovascular events and strokes and has been withdrawn from the market in several countries and regions.