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.
2008
[[There is no material yet from my new site.]]
Outside resources:
- 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.
- 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].
- 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].
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
2010-04-11. 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
- Stats: The stubborn
insistence on placebos (June 29, 2007). The patients who volunteer for a
randomized trial are sacrificing a great deal of autonomy. They giving up the
right to determine which drug they get and they are ceding this authority not
to an expert but to a random device. You should not abuse that gift by asking
them to participate in a trial where they have a 50% chance of getting a
treatment that is known to be inferior. This is especially difficult when one
of the choices is a placebo. There is a hot debate about when a placebo arm
is ethically acceptable.
- Stats: The trouble with
apples and oranges (June 25, 2007). I am still working on the details of
a presentation for the Kansas City University of Medicine and Biosciences.
They want me to talk at lunch during the 2007 Homecoming CME and Reunion
weekend. The new title is "Medical Journals - The Trouble with Apples and
Oranges."
- Stats: When bad control groups
happen to good researchers (June 15, 2007). The Kansas City University of
Medicine and Biosciences wants me to give a light humorous talk at lunch
during the 2007 Homecoming CME and Reunion weekend. Somehow, they provided me
with a title for my talk, "Humor, Databases and Grant Proposals: What Strange
Bedfellows" which is a fine title, but not the one I would have chosen. I'll
talk it over with the organizers, but here's a possible choice: "When bad
control groups happen to good researchers".
2006
- Stats: The tension between
scientific validity and ethical concerns (November 17, 2006). A question
on the IRB Forum email discussion group (from RI) centered on the ethical
concerns about using a placebo arm in a study involving control of pain.
There are scientific reasons why a placebo control group are important, but
is it ethical to ask research subjects to possibly endure some greater level
of pain in order to achieve certain scientific goals?
- Stats: Ethical concerns about a placebo
run-in (created 2006-10-04). Dear Professor Mean, Some of the
trials that our Institutional Review Board looks at have a placebo run-in
period. All patients are given a placebo before the start of treatment and
anyone who responds well to the placebo is dropped from the trial. What are
the ethical ramifications of such a study. You can't disclose the placebo
run-in period to the research volunteers because it would defeat the purpose.
Updated 2010-02-04.
2005
- Stats: Patients' reactions to
finding out they were in the placebo group (May 11, 2005). A lot of
people have written a lot of things about the use of placebos in research,
but one group that hasn't been heard from nearly enough is the patients
themselves. A recently published article has changed that trend.
2004
- Stats: Excluding placebo responders
(June 25, 2004). I've always been fascinated by the placebo effect and
the ethical issues associated with use of placebos in research. A
correspondent in the IRBForum email discussion group asked about the recent
efforts of drug companies to identify patients who are likely to show a
placebo effect and then exclude them from randomized trials.
2001
- Stats: Ethics of a placebo group (August 2,
2001). Dear Professor Mean, Some of my colleagues want to use
placebos in their research, but I have warned them about the ethical issues
surrounding the use of a placebo group. When (if ever) is it ethical to use a
placebo group? --Kibitzing Kathy
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