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The Effect of Placebo on Weight Loss in Obese Patients: A Meta-analysis

Class of 2008 Abstract / Objectives: To assess the effect of treatment with placebo on weight loss in obese patients.
Methods: The placebo groups from nine orlistat and three sibutramine weight loss studies, as identified from the Padwal meta-analysis, were analyzed for: weight loss in kilograms; change in BMI; type of nutrition and exercise interventions; and bias. The means and standard deviations for weight loss were entered into the Stata meta-analysis program to obtain a forest plot to determine an overall estimate of weight loss. The Potential for Methodological Bias Assessment Tool (PMBAT) was used to create a bias score for each study.
Results: Overall, subjects in the placebo group lost 3.8 kg (p<0.001). Placebo subjects in the orlistat trials lost significantly more weight (4.3 kg) than did subjects in the sibutramine trials (1.1 kg, p=0.014). The subjects in the sibutramine studies did not lose a significant amount of weight (p=0.397). There were distinct differences between the sibutramine and orlistat studies with regard to nutrition and exercise interventions. The mean score on the PMBAT was 16.7 ± 3.6; and no study scored higher than 25 out of 45 total points.
Conclusions: Overall subjects in the placebo group in the combined orlistat and sibutramine studies lost a significant amount of weight. Differences in study design, bias, and the Hawthorne effect may have contributed to this weight loss.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624317
Date January 2008
CreatorsBurke, Eric, Garvin, Matthew
ContributorsSlack, Marion, College of Pharmacy, The University of Arizona
PublisherThe University of Arizona.
Source SetsUniversity of Arizona
Languageen_US
Detected LanguageEnglish
Typetext, Electronic Report
RightsCopyright © is held by the author.

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