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Long-term pharmacotherapy for obesity and overweight

  1. R Padwal Clinical Fellow*,
  2. SK Li,
  3. DCW Lau

Editorial Group: Cochrane Metabolic and Endocrine Disorders Group

Published Online: 22 JUL 2002

DOI: 10.1002/14651858.CD004094


How to Cite

Padwal R, Li SK, Lau DCW. Long-term pharmacotherapy for obesity and overweight. The Cochrane Database of Systematic Reviews 2002, Issue 3. Art. No.: CD004094. DOI: 10.1002/14651858.CD004094.

Author Information

  1. Sunnybrook and Women's College Health Sciences Center, Division of Clinical Pharmacology, Toronto, Ontario, CANADA

*R Padwal, Clinical Fellow, Division of Clinical Pharmacology, Sunnybrook and Women's College Health Sciences Center, Room E2-42, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, CANADA. rpadwal@yahoo.com.

Publication History

  1. Published Online: 22 JUL 2002

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Abstract

  1. Top of page
  2. Abstract
  3. Synopsis

Background

Worldwide prevalence rates of obesity and overweight are rising and safe and effective treatment strategies are urgently needed. A number of anti-obesity agents have been studied in short-term clinical trials, but long-term efficacy and safety need to be established.

Objectives

To assess/compare the effects and safety of approved anti-obesity medications in clinical trials of at least one-year duration.

Search strategy

MEDLINE, EMBASE, the Cochrane Controlled Trials Register, the Current Science Meta-register of Controlled Trials, and reference lists of original studies and reviews were searched. Date of last search was December 2002. Drug manufacturers and two obesity experts were contacted in to detect unpublished trials. No language restrictions were imposed.

Selection criteria

Double-blind, randomised controlled weight loss and weight maintenance trials of approved anti-obesity agents that 1) enrolled adult overweight or obese patients, 2) included a placebo control group or compared two or more anti-obesity drugs 3) used an intention-to-treat analysis, and 4) had a minimum follow-up period of one year. Abstracts and pseudo-randomised trials were not included.

Data collection and analysis

Two reviewers independently assessed all potentially relevant citations for inclusion and methodological quality. The primary outcome measure was weight loss.

Main results

Of the eight anti-obesity agents investigated, only orlistat and sibutramine trials met inclusion criteria. Eleven orlistat weight loss studies (four of which reported a second year weight maintenance phase) and five sibutramine studies (three weight loss and two weight maintenance trials) were included. Attrition rates averaged 33% during the weight loss phase of orlistat trials and 43% in sibutramine studies. 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 kg to 4.9 kg) 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. Orlistat caused gastrointestinal side effects and sibutramine was associated with small increases in blood pressure and pulse rate.

Reviewers' conclusions

Studies evaluating the long-term efficacy of anti-obesity agents are limited to orlistat and sibutramine. Both drugs appear modestly effective in promoting weight loss; however, interpretation is limited by high attrition rates. Longer and more methodologically rigorous studies of anti-obesity drugs that are powered to examine endpoints such as mortality and cardiovascular morbidity are required to fully evaluate any potential benefit of such agents.

 

Synopsis

  1. Top of page
  2. Abstract
  3. Synopsis

Synopsis

LONG-TERM PHARMACOTHERAPY FOR OBESITY AND OVERWEIGHT

This review assessed the long-term efficacy and safety of all approved anti-obesity medications in clinical trials of at least one-year duration. Eleven orlistat and five sibutramine studies met inclusion criteria and the primary outcome measure was weight loss. Interpretation of results is limited due to high study attrition rates. Compared to placebo, both medications produced average weight losses of less than five kilograms. Orlistat increased gastrointestinal side effects and sibutramine caused small increases in blood pressure and pulse rate. We conclude that: 1. average weight loss with current anti-obesity agents appears modest, and 2. more methodologically rigorous studies that are powered to examine mortality and cardiovascular morbidity are required to fully evaluate any potential benefit of such agents.