Prevalence and factors associated with use of placebo control groups in randomized controlled trials in psoriasis: A cross-sectional study - 09/08/11
Reprint requests: David J. Margolis, MD, PhD, Associate Professor of Dermatology and Epidemiology, University of Pennsylvania School of Medicine, 815 Blockley Hall, 423 Guardian Dr, Philadelphia, PA 19104.Philadelphia, Pennsylvania
Abstract |
Background |
The ethics and science of using placebo control groups in clinical trials have been widely debated. Few studies, however, have examined factors associated with choice of control group.
Objective |
Our aim was to assess the prevalence of use of placebo controls in randomized controlled trials in psoriasis and to identify factors associated with use of placebo controls in these trials.
Methods |
This is a cross-sectional study of randomized controlled trials in psoriasis published from January 1, 2001 to December 20, 2005 and indexed in the Cochrane Central Register of Controlled Trials. We extracted data on types of control groups used, design issues (number of patients enrolled, primary end point), disease characteristics (psoriasis type and severity), and extrascientific issues (trial location, funding source, and year of publication). We used bivariable and multivariable logistic regression to determine factors associated with use of a placebo control group.
Results |
Of 194 citations, 187 were available for review. One hundred thirty-five trials from 134 articles in 38 journals met inclusion criteria. Eighty-three trials (61.5%) enrolling 8171 subjects (41.7%) used active controls only, and 52 trials (38.5%) enrolling 11,406 subjects (58.3%) used placebo controls. Adjusted for trial location and funding source, trials significantly more likely to have used placebo controls included those conducted in the United States (odds ratio [OR], 5.79; 95% confidence interval [CI], 2.45-13.68; P < .001) and those funded by pharmaceutical companies (OR, 2.61; 95% CI, 1.19-5.73; P = .02). Predicted frequencies of placebo use ranged from 77.6% (industry-funded, conducted trials in the United States) to 18.6% (non-industry-funded trials not conducted in the United States).
Limitations |
Our searches may not have identified all published trials, and we did not have access to data from unpublished trials.
Conclusions |
Use of placebo controls has been more common in psoriasis trials conducted in the United States and funded by pharmaceutical companies. The findings suggest that ethical and scientific issues related to choice of control group in psoriasis trials are interpreted markedly differently depending on trial location and funding source.
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| Funding sources: Dr Katz’s fellowship was funded by a Kirschstein National Research Service Award from the National Institutes of Health. Dr Karlawish is funded by a Greenwall Faculty Scholar in Bioethics award. Disclosure: Dr Karlawish receives grant funding from Wyeth Pharmaceuticals and is a consultant for Wyeth Pharmaceuticals, Myriad Pharmaceuticals, and Elan. Dr Margolis serves on safety advisory boards for Abbott, Astellas, Biogen Idec, and Centocor. |
Vol 55 - N° 5
P. 814-822 - novembre 2006 Retour au numéro
Article précédent
- A phase II open-label study of recombinant human interleukin-12 in patients with stage IA, IB, or IIA mycosis fungoides
- Madeleine Duvic, Matthew L. Sherman, Gary S. Wood, Timothy M. Kuzel, Elise Olsen, Francine Foss, Robert J. Laliberté, John L. Ryan, Kristilyn Zonno, Alain H. Rook
- Registration of clinical trials
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