A Cochrane review included eleven orlistat weight loss studies with 7 180 subjects and five sibutramine studies with 1 556 subjects (three weight loss and two weight maintenance trials) of at least one-year duration. All patients received lifestyle modification as a co-intervention.
Compared to placebo, orlistat-treated patients lost 2.7 kg (95% CI 2.3 kg to 3.1 kg) or 2.9% (95% CI 2.3 to 3.4) more weight and patients on sibutramine experienced 4.3 kg (95% CI 3.6 to 4.9) or 4.6% (95% CI 3.8 to 5.4) greater weight loss. The number of patients achieving ten percent or greater weight loss was 12% (95% CI 8 to 16) higher with orlistat and 15% (95% CI 4 to 27) higher with sibutramine therapy. Weight loss maintenance results were similar. Interpretation of the results is limited by high attrition rates which averaged 33% during the weight loss phase of orlistat trials and 43% in sibutramine studies.
Comment: The quality of evidence is downgraded by study quality (more than 20% loss to follow up). Sibutramine was suspended from market in January 2010 due to an increase of cardiovascular risk.