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Michael,
I agree. Your goat/unicorn summary is one I will use again, but to put the
point even more succinctly:
"Extraordinary claims require extraordinary evidence.." - Carl Sagan I
think.
Mike Bennett
-----Original Message-----
From: Evidence based health (EBH)
[mailto:[log in to unmask]] On Behalf Of Michael Power
Sent: Tuesday, 6 January 2009 8:25 AM
To: [log in to unmask]
Subject: Re: Fw: Special Issue:Evidence in Evidence-Based Medicine Fw:
Social Epistemology - informaworld
Ben
I think that you are wrong when you say "EBM does not have a consistent
stand on the issue", "i.e. whether evidence trumps theory or theory comes
prior to evidence".
The issue you raise boils down to "when should a scientist NOT believe
anomalous evidence that seems to contradict established theory".
For example, when an RCT of a homeopathic remedy is positive, this
contradicts established scientific theory that pure water (the homeopathic
remedy) delivered theatrically should have no more effect than a placebo
delivered with the same theatricality.
EBM (and science in general) *is* consistently sceptical about anomalous
results. John Ioannidis has some great empirical evidence why this should be
so for EBM. See his paper "Why most published research findings are false",
which is freely available at
www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1182327.
The problem of how to interpret the anomalous experimental result has been
much debated by philosophers of science. You can find an excellent
introduction to the issues here:
http://apgaylard.wordpress.com/2008/02/03/expect-the-unexpected, and the two
subsequent blog postings. The blog is quite long and detailed, and I won't
attempt to summarize it here.
But, there is a clear analogy (which I think I read in the book "Trick or
treatment" by Simon Singh and Edzard Ernst), which makes the point in two
short sentences:
If my wife calls me at work and says that there is a goat in the garden, I
will believe her - I live on a farm, and we do get trespassers in the garden
from time to time.
But, if she says that she has seen a unicorn in the garden, I want more
corroborating evidence, such as a zoologist's report that the horn on the
animal's head hasn't been glued on.
As Colleen Derkatch (Social Epistemology 2008; 22(4): 371-388) might say,
arguments about the priority of evidence or theory can be read,
metonymically, as expressions of anxiety about goats or unicorns in the
garden.
I hope this clarifies EBM's epistemological stand.
Michael
-----Original Message-----
From: Djulbegovic, Benjamin [mailto:[log in to unmask]]
Sent: 05 January 2009 18:30
To: Michael Power; [log in to unmask]
Subject: RE: Fw: Special Issue:Evidence in Evidence-Based Medicine Fw:
Social Epistemology - informaworld
In fact, CAM research such as homeopathy RCTs represents one of the great
challenges and opportunities for EBM to clarify its epistemological stand.
It deals with eternal scientific question which comes first : evidence or
theory i.e. whether evidence trumps theory or theory comes prior to
evidence. In fact, it has been shown that EBM does not have consistent stand
on the issue. On one hand, EBM movement has documented numerous examples
when getting our evidence right overturned the prevailing theory of the day
(e.g. findings from the RCT that tested the effects of hormone-replacement
therapy resulted in a dramatic abandonment of theory claiming that estrogen
can help reduce risk of coronary disease despite a score of observational
studies i.e. lower quality evidence supporting the estrogen theory).
However, results of RCT homeopathy trials were largely dismissed not because
of lower quality evidence (many of these trials were high-quality
placebo-controlled trials) but because of poorly formulated theory which
does not correspond to the contemporary physical and chemical principles
(homeopathic drugs are prepared by serial dilutions of remedy, the result of
which is that "drug" is diluted beyond the point where there is any
likelihood that a single molecule from the original solution is present in
the final product). In this case, the lack of credible theory trumped
seemingly rigorously obtained observations.
ben
Benjamin Djulbegovic, MD, PhD
Professor of Medicine and Oncology
Co-Director of Clinical Translation Science Institute Director of Center for
Evidence-based Medicine and Health Outcomes Research
Mailing Address:
USF Health Clinical Research
12901 Bruce B. Downs Boulevard, MDC02
Tampa, FL 33612
Phone # 813-396-9178
Fax # 813-974-5411
e-mail: [log in to unmask]
______________________
Campus Address: MDC02
Office Address :
13101 Bruce B. Downs Boulevard,
CMS3057
Tampa, FL 33612
-----Original Message-----
From: Evidence based health (EBH)
[mailto:[log in to unmask]] On Behalf Of Michael Power
Sent: Monday, January 05, 2009 10:43 AM
To: [log in to unmask]
Subject: Re: Fw: Special Issue:Evidence in Evidence-Based Medicine Fw:
Social Epistemology - informaworld
<snip>
CAM can't be tested by RCTs because "Randomisation and standardisation are
foreign, and often incommensurate, concepts in CAM"
<snip>
I find it fascinating that The British Homeopathic Association (BHA) does
not agree that CAM can't be tested by RCTs. Their website
(www.trusthomeopathy.org) states "There are over 50 randomised controlled
trials demonstrating homeopathy has a positive effect."
Of course, and this is a key difference between CAM and EBM, it does not say
how well these studies were designed, conducted, and analysed. Nor does it
say how many negative trials there are. If you look in the Cochrane Library
you will find 5 systematic reviews of homeopathy for attention
deficit/hyperactivity disorder, asthma, dementia, nocturnal enuresis,
influenza, and induction of labour. The reviews found 29 RCTs, mostly of
poor quality, and none providing evidence strong enough to support the use
of homeopathy.
I expect that, when I read the Social Epistemology articles, I will find the
claim that CAM can't be tested for specific conditions because it treats the
patient holistically. So, it is interesting to see that the BHA has found
positive evidence for the following "conditions" (the scare quotes indicate
that this is the term used by the BHA, but that some "conditions" would not
be classified as such by a medical doctor).
Allergic asthma
Anal fissure
Ankle sprain
Attention deficit hyperactivity disorder Brain injury Bronchitis Cardiac
insufficiency Childhood diarrhoea Childhood fever Chronic fatigue syndrome
Common cold Cough Dry mouth Fibromyalgia Gastrointestinal cramps Hay fever
Headache HIV infection Immune function Infertility (female) Influenza
Irritable bowel syndrome Kidney failure Low back pain Migraine Muscle
soreness Obesity Osteoarthritis Otitis media Plantar fasciitis
Post-operative agitation Post-operative bruising, pain or swelling
Post-operative ileus Post-partum bleeding Post-partum lactation problems
Premenstrual syndrome Pruritis Radiotherapy-induced dermatitis Respiratory
tract infection Seborrhoeic dermatitis Sepsis Sinusitis Stomatitis
Tendinopathy Tracheal secretions Varicose veins Vertigo Viral infection
A pubmed search found a meta-analysis of trials of homeopathy for
postoperative ileus. The abstract does not say how many trials were found,
but it does say that the primary outcome was time to first flatus.
I think I need a breath of fresh air!
Michael
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