Context: Safe and effective strategies to curb rising obesity prevalence rates are urgently needed and medications may play a more prominent role in future therapeutic regimens.
Objective: To review systematically the long-term efficacy and safety of approved antiobesity medications.
Data sources: MEDLINE, EMBASE, the Cochrane Controlled Trials Register, Current Science Meta-register of Controlled Trials, and reference lists of original studies and reviews were searched. Drug manufacturers and two obesity experts were contacted. No language restrictions were imposed.
Study selection: Double-blind, randomized controlled studies of approved antiobesity medications with follow-up periods of 1 y or greater were eligible for inclusion.
Data extraction: Two reviewers independently assessed all potentially relevant studies for inclusion and methodological quality using standardized abstraction forms.
Results: A total of 11orlistat (n=6021) and three sibutramine (n=929) studies met inclusion criteria. Attrition rates averaged 33% in orlistat studies and 48% in sibutramine studies. A random effects model was used for meta-analysis. Compared to placebo, orlistat-treated patients displayed a 2.7 kg (95% CI: 2.3-3.1 kg) or 2.9% (95% CI: 2.3-3.4%) greater reduction in weight and patients on sibutramine displayed a 4.3 kg (95% CI: 3.6-4.9 kg) or 4.6% (95% CI: 3.8-5.4%) greater weight reduction after 1 y of follow-up. The number of patients achieving 10% or greater weight loss was 12% (95% CI: 8-16%) higher with orlistat and 15% (95% CI: 4-27%) higher with sibutramine compared to placebo. Orlistat caused gastrointestinal side effects and sibutramine increased blood pressure and pulse rate.
Conclusion: There is a relative paucity of long-term studies of antiobesity agents. In weight loss trials of 1-y duration, orlistat and sibutramine appear modestly effective in promoting weight loss. Longer, more methodologically rigorous studies that are powered to examine end points such as mortality and cardiovascular morbidity are required.