|
|
P.Mean >>
Category >> Placebo controlled trials (created 2007-06-26).
|
A placebo is an inert substance that looks and tastes like an active drug, which is used in research studies to provide a blinded comparison group for the active drug. In a study of a medical device or a physical intervention, the placebo takes a different form. Placebo controlled trials raise difficult ethical and logistical concerns. Also see Category: Blinding in research, Category: Equipoise in research, Category: Ethics in research. Other entries about placebo controlled trials can be found in the placebo controlled trials page at the StATS website.
2011
P.Mean: Cartoon about placebos (created 2011-06-14). I drew a small cartoon about placebos. I know you think that this is drawn by a professional artist, but I did this. Really!
SJ Senn. Are placebo run ins justified? BMJ 1997: 314(7088); 1191-3. [Medline] [Full text]. Description: This article criticizes the use of placebos at the start of a study to estimate compliance patterns and to potentially exclude patients who do not comply well with the research protocol. The author argues that this practice is deceptive and leads to poor science.
Steve Draper. The Hawthorne effect: a note. This website was last verified on 2008-01-14. URL: www.psy.gla.ac.uk/~steve/hawth.html
John E. Dodes. The Mysterious Placebo. Description: Published in the January/February 1997 issue of Skeptical Inquirer. A nice overview of the placebo effect and how it influences the study of alternative medicines. This website was last verified on 2008-01-14. URL: www.csicop.org/si/9701/placebo.html
T. J. Kaptchuk, J. M. Kelley, L. A. Conboy, R. B. Davis, C. E. Kerr, E. E. Jacobson, I. Kirsch, R. N. Schyner, B. H. Nam, L. T. Nguyen, M. Park, A. L. Rivers, C. McManus, E. Kokkotou, D. A. Drossman, P. Goldman, A. J. Lembo. Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome. Bmj 2008: 336(7651); 999-1003. [Medline] [Abstract] [Full text] [PDF]. Description: The authors suggest that the placebo affect can be separated into three components: the process of observation itself (the Hawthorne effect), the therapeutic ritual associated with a placebo, and the patient-practitioner interactions. They then test this empirically in a three arm single blind study. There were significant differences between the arms of the study, and the effect of the patient-practitioner interactions was the strongest effect.
Edzard Ernst. Homeopathy, non-specific effects and good medicine. Rheumatology. Excerpt: "In this issue, Brien et al. [1] report the findings of a five-armed randomized controlled trial, which was aimed at differentiating between the effects of homeopathic remedies and patient consultations. The authors demonstrate that homeopathic remedies are placebos and show that ‘the benefits of homeopathy are attributable to the consultation’ [1]. Critics of homeopathy have always pointed out that homeopathic remedies are so highly dilute that they must be devoid of specific therapeutic effects. They are biologically implausible [2], and the ∼150 published trials collectively fail to indicate clinical effectiveness [3]. At the same time, we know from several observational studies (e.g. [4]) that patients do improve after consulting a homeopath. " [Accessed December 20, 2010]. Available at: http://rheumatology.oxfordjournals.org/content/early/2010/11/08/rheumatology.keq265.short.
Lund I, Naslund J, Lundeberg T. Minimal acupuncture is not a valid placebo control in randomised controlled trials of acupuncture: a physiologist's perspective. Chinese Medicine. 2009;4(1):1. Available at: http://www.cmjournal.org/content/4/1/1 [Accessed February 10, 2009].
Journal article: Paul Enck, Sibylle Klosterhalfen, Stephan Zipfel. Novel study designs to investigate the placebo response BMC Medical Research Methodology. 2011;11(1):90. Abstract: "BACKGROUND: Investigating the size and mechanisms of the placebo response in clinical trials have relied on experimental procedures that simulate the double-blind randomized placebo-controlled design. However, as the conventional design is thought to elucidate drug rather than placebo actions, different methodological procedures are needed for the placebo response. Methods: We reviewed the respective literature for trials designs that may be used to elucidate the size of the placebo response and the mechanisms associated with it. Results: In general, this can be done by either manipulation the information provided to the subjects, or by manipulation the timing of the drug applied. Two examples of each strategy are discussed: the "balanced placebo design" (BDP) and the "balanced cross-over design" (BCD) and their variants are based on false information, while the "hidden treatment" (HT) and the ""delayed response test" (DRT) are based on manipulating the time of drug action. Since most such approaches include deception or incomplete information of the subjects they are suitable for patient only with authorized deception. Conclusion: Both manipulating the information provided to subjects (BDP, DCD) or manipulating the timing of drug application (HT, DRT) allows overcoming some of the restrictions of conventional drug trials in the assessment of the placebo response, but they are feasible mostly in healthy subjects for ethical reasons." [Accessed on June 14, 2011]. http://www.biomedcentral.com/1471-2288/11/90
Robert Todd Carroll. The Placebo Effect. Excerpt: The placebo effect is the measurable, observable, or felt improvement in health not attributable to treatment. This effect is believed by many people to be due to the placebo itself in some mysterious way. A placebo (Latin for “I shall please”) is a medication or treatment believed by the administrator of the treatment to be inert or innocuous. Placebos may be sugar pills or starch pills. Even “fake” surgery and “fake” psychotherapy are considered placebos. This website was last verified on 2008-01-14. URL: www.skepdic.com/placebo.html
Zelda Di Blasi, Fay Crawford, Colin Bradley, Jos Kleijnen. Reactions to treatment debriefing among the participants of a placebo controlled trial. BMC Health Services Research. 2005;5(1):30. Abstract: "BACKGROUND: A significant proportion of trial participants respond to placebos for a variety of conditions. Despite the common conduct of these trials and the strong emphasis placed on informed consent, very little is known about informing participants about their individual treatment allocation at trial closure. This study aims to address this gap in the literature by exploring treatment beliefs and reactions to feedback about treatment allocation in the participants of a placebo-controlled randomized clinical trial (RCT). METHODS: Survey of trial participants using a semi-structured questionnaire including close and open-ended questions administered as telephone interviews and postal questionnaires. Trial participants were enrolled in a double-blind placebo-controlled RCT evaluating the effectiveness of corticosteroid for heel pain (ISRCTN36539116). The trial had closed and participants remained blind to treatment allocation. We assessed treatment expectations, the percentage of participants who wanted to be informed about their treatment allocation, their ability to guess and reactions to debriefing. RESULTS: Forty-six (73%) contactable participants responded to our survey. Forty-two were eligible (four participants with bilateral disease were excluded as they had received both treatments). Most (79%) participants did not have any expectations prior to receiving treatment, but many 'hoped' that something would help. Reasons for not having high expectations included the experimental nature of their care and possibility that they may get a placebo. Participants were hopeful because their pain was so severe and because they trusted the staff and services. Most (83%) wanted to be informed about their treatment allocation and study results. Over half (55%) said they could not guess which treatment they had been randomized to, and many of those who attempted a guess were incorrect. Reactions to treatment debriefing were generally positive, including in placebo responders. CONCLUSION: Our study suggests that most trial participants want to be informed about their treatment allocation and trial results. Further research is required to develop measure of hope and expectancy and to rigorously evaluate the effects of debriefing prospectively." [Accessed February 3, 2010]. Available at: http://www.biomedcentral.com/1472-6963/5/30.
Krogsboll L, Hrobjartsson A, Gotzsche P. Spontaneous improvement in randomised clinical trials: meta-analysis of three-armed trials comparing no treatment, placebo and active intervention. BMC Medical Research Methodology. 2009;9(1):1. Available at: http://www.biomedcentral.com/1471-2288/9/1 [Accessed February 23, 2009].
TheProfessorFunk. The Strange Powers of the Placebo Effect.; 2011. Abstract: "A look at the many strange effects of placebos. Created by: Daniel Keogh - http://www.twitter.com/ProfessorFunk, Luke Harris - http://www.lukeharrisgraphics.com. Sources: Ben Goldacre's book 'Bad Science' has an excellent chapter on placebos http://www.badscience.net/, http://www.amazon.co.uk/Bad-Science-Ben-Goldacre/dp/000728487X/?tag=bs0b-21. The Wikipedia page on Placebos is pretty excellent too: http://en.wikipedia.org/wiki/Placebo." [Accessed March 3, 2011]. Available at: http://www.youtube.com/watch?v=yfRVCaA5o18.
Beatrice A. Golomb, Laura C. Erickson, Sabrina Koperski, et al. What's in Placebos: Who Knows? Analysis of Randomized, Controlled Trials. Annals of Internal Medicine. 2010;153(8):532 -535. Abstract: "Background: No regulations govern placebo composition. The composition of placebos can influence trial outcomes and merits reporting. Purpose: To assess how often investigators specify the composition of placebos in randomized, placebo-controlled trials. Data Sources: 4 English-language general and internal medicine journals with high impact factors. Study Selection: 3 reviewers screened titles and abstracts of the journals to identify randomized, placebo-controlled trials published from January 2008 to December 2009. Data Extraction: Reviewers independently abstracted data from the introduction and methods sections of identified articles, recording treatment type (pill, injection, or other) and whether placebo composition was stated. Discrepancies were resolved by consensus. Data Synthesis: Most studies did not disclose the composition of the study placebo. Disclosure was less common for pills than for injections and other treatments (8.2% vs. 26.7%; P = 0.002). Limitation: Journals with high impact factors may not be representative. Conclusion: Placebos were seldom described in randomized, controlled trials of pills or capsules. Because the nature of the placebo can influence trial outcomes, placebo formulation should be disclosed in reports of placebo-controlled trials. Primary Funding Source: University of California Foundation Fund 3929—Medical Reasoning." [Accessed October 19, 2010]. Available at: http://www.annals.org/content/153/8/532.abstract.
All of the material above this paragraph is licensed under a
Creative Commons Attribution 3.0 United States License. This page was written by
Steve Simon and was last modified on
2011-01-01. The material
below this paragraph links to my
old website, StATS. Although I wrote all of the material
listed below, my ex-employer, Children's Mercy Hospital, has claimed copyright
ownership of this material. The brief excerpts shown here are included under
the fair use provisions of U.S. Copyright laws.
2007
What now?
Browse other categories at this site
