Placebo: Difference between revisions
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A '''placebo''' is any medication or treatment expected to have no physiological effect; the generally synonymous term '''sham treatment''' is sometimes used to describe a surgical or other procedure, more visible than a pill. According to the [[United States]] [[National Library of Medicine]], a placebo is defined as a "dummy medication or treatment. Although placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition, the concept has been extended to include treatments or procedures, especially those administered to control groups in clinical trials in order to provide baseline measurements for the experimental protocol."<ref>{{MeSH}}</ref> | A '''placebo''' is any medication or treatment expected to have no physiological effect; the generally synonymous term '''sham treatment''' is sometimes used to describe a surgical or other procedure, more visible than a pill. According to the [[United States]] [[National Library of Medicine]], a placebo is defined as a "dummy medication or treatment. Although placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition, the concept has been extended to include treatments or procedures, especially those administered to control groups in clinical trials in order to provide baseline measurements for the experimental protocol."<ref>{{MeSH}}</ref> | ||
==Placebo versus placebo effect== | |||
Placebo is different from a placebo effect, which is defined as an "effect usually, but not necessarily, beneficial that is attributable to an expectation that the regimen will have an effect, i.e., the effect is due to the power of suggestion"<ref>{{MeSH|Placebo effect}}</ref> Thus the placebo effect can be a component of the effect of a treatment that has a true physiologic role; whereas a placebo has no intention of physiologic benefit. | Placebo is different from a placebo effect, which is defined as an "effect usually, but not necessarily, beneficial that is attributable to an expectation that the regimen will have an effect, i.e., the effect is due to the power of suggestion"<ref>{{MeSH|Placebo effect}}</ref> Thus the placebo effect can be a component of the effect of a treatment that has a true physiologic role; whereas a placebo has no intention of physiologic benefit. | ||
The placebo effect is very common. In a [[randomized controlled trial]] of [[pregabalin]] for [[fibromyalgia]] the following occurred:<ref name="pmid18278830">{{cite journal |author=Mease PJ, Russell IJ, Arnold LM, ''et al'' |title=A randomized, double-blind, placebo-controlled, phase III trial of pregabalin in the treatment of patients with fibromyalgia |journal=The Journal of Rheumatology |volume=35 |issue=3 |pages=502–14 |year=2008 |month=March |pmid=18278830 |doi= |url=http://www.jrheum.com/subscribers/08/03/502.html |issn=}} Trial registration number not provided by authors, but is likely to be [http://clinicaltrials.gov/ct2/show/NCT00333866 NCT00333866]</ref> | |||
{| class="wikitable" | |||
|+ A randomized controlled trial of <br>pregabalin versus placebo <br>for fibromyalgia | |||
! study group!! Patients reporting at least <br>"much" improvement in their pain | |||
|- | |||
| pregabalin|| align="center"|43% | |||
|- | |||
| placebo|| align="center"|35% | |||
|} | |||
Among the patients who received pregabalin, most of the benefit was due to placebo effect. The benefit due to the drug was 43% minus 35% or 8%. Thus if 100 patients receive pregabalin: | |||
* 35 will improve due to placebo effect | |||
* 8 will improve due to pregabalin | |||
* 57 will not improve | |||
==Purpose== | ==Purpose== | ||
Revision as of 10:15, 24 October 2008
A placebo is any medication or treatment expected to have no physiological effect; the generally synonymous term sham treatment is sometimes used to describe a surgical or other procedure, more visible than a pill. According to the United States National Library of Medicine, a placebo is defined as a "dummy medication or treatment. Although placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition, the concept has been extended to include treatments or procedures, especially those administered to control groups in clinical trials in order to provide baseline measurements for the experimental protocol."[1]
Placebo versus placebo effect
Placebo is different from a placebo effect, which is defined as an "effect usually, but not necessarily, beneficial that is attributable to an expectation that the regimen will have an effect, i.e., the effect is due to the power of suggestion"[2] Thus the placebo effect can be a component of the effect of a treatment that has a true physiologic role; whereas a placebo has no intention of physiologic benefit.
The placebo effect is very common. In a randomized controlled trial of pregabalin for fibromyalgia the following occurred:[3]
| study group | Patients reporting at least "much" improvement in their pain |
|---|---|
| pregabalin | 43% |
| placebo | 35% |
Among the patients who received pregabalin, most of the benefit was due to placebo effect. The benefit due to the drug was 43% minus 35% or 8%. Thus if 100 patients receive pregabalin:
- 35 will improve due to placebo effect
- 8 will improve due to pregabalin
- 57 will not improve
Purpose
Placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition. They have been used as a means of suggestion to individual patients. A randomized controlled trial found that placebo medications that the patient perceives as more expensive will have more placebo effect than placebos that are percieved as less expensive.[4]
|
In any medical study, every patient- including those of a control group, if any- should be assured of the best proven diagnostic and therapeutic method. From The Declaration of Helsinki[5] |
The more common use of placebos is as for the patients in the control group of a randomized controlled trial. The World Medical Organization's interpretation of the Declaration of Helsinki, says placebo controls are unethical if there is a standard treatment for the disease being studied.[5] When no treatment is available, placebo controls are ethical. This is by no means agreed by all medical scientists.
References
- ↑ Anonymous (2024), Placebo (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ Anonymous (2024), Placebo effect (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ Mease PJ, Russell IJ, Arnold LM, et al (March 2008). "A randomized, double-blind, placebo-controlled, phase III trial of pregabalin in the treatment of patients with fibromyalgia". The Journal of Rheumatology 35 (3): 502–14. PMID 18278830. [e] Trial registration number not provided by authors, but is likely to be NCT00333866
- ↑ Waber RL, Shiv B, Carmon Z, Ariely D (March 2008). "Commercial features of placebo and therapeutic efficacy". JAMA : the journal of the American Medical Association 299 (9): 1016–7. DOI:10.1001/jama.299.9.1016. PMID 18319411. Research Blogging.
- ↑ 5.0 5.1 Rickham PP (July 1964). "Human Experimentation. Code of Ethics of the World Medical Association. Declaration of Helsinki". British Medical Journal 2 (5402): 177. PMID 14150898. PMC 1816102. [e]
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