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message sent to several lists;
apologies for duplicate copies
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many thanks to those of you that were kind enough to respond
to my request for information on the above (see end of email)
replies seem to have dried up now ( i would still like further
information if any one has any ) and so ive copied below those
received to date - thanks again, rob manning, economics, york.
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> TRY:
> Abstracts in
> J Ep Comm Health:
> Society of Social Medicine
> Cardiff meeting
> Sept 23rd 1998
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> a good start would be
> Jadad AR Moore RA Carroll D et al
> Assessing the quality of randomized controlled trials:
is blinding necessary?
> Controlled Clinical Trials 1996; 17: 1-12.
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> You asked about studies which quantify bias caused by lack of
blinding. I talk about this in section 3.1 of my web presentation,
How to Read a Medical Journal Article (see below for the URL).
Here are three references that I use in that discussion.
>
> Colditz GA, Miller JN, Mosteller F. How study design affects
outcomes in comparisons of therapy. I: Medical. Stat Med, 8: 441-454
(1989).
>
> Nelemans PJ, Rampen FHJ, Ruiter DJ, Verbeek ALM. "An addition to the
> controversy on sunlight exposure and melanoma risk: a
meta-analytical
> approach." Journal of Clinical Epidemiology, 48: 1331-1342 (1995).
>
> Schulz, KF. Randomised trials, human nature, and reporting
guidelines. Lancet, 348: 596-598 (1996).
>
> Steve Simon, [log in to unmask], Standard Disclaimer.
> How to Read a Medical Journal Article:
http://www.cmh.edu/stats/journal.htm
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> no I don't know of any studies BUT we had a talk on evidence based
medicine and some figures on a slide that indicated biases in
treatment effect due to (lack of) certain elements in study design.
> Randomisation 40%
> Double blind 17%
[ rm108: see
http://www.jr2.ox.ac.uk/bandolier/band17/b17-4.html
for this table, which is from the schultz jama article ]
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> Schultz KF Subverting randomization in controlled trials Jama 1995
>
> White K et al Side effects and the blindability of clinical drug
trials. American Journal of Psychiatry 1992> >
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> as well as the Ken Schulz stuff, there is a paper by David Moher in
> Lancet August 22nd 98. There is also an accompanying editorial.
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> I would look at trials of TENS machines and low dose tricyclic
> antidepressants for pain. Both of these show diminished efficacy as
better blinding to active/placebo is put in place. Henry McQuay at the
Oxford Pain Research Group (and Bandolier) knows much more than me...
......................................
On Thu, 8 Oct 1998, rob wrote:
> dear recipient
>
> do you know of any studies that have been
> undertaken / published that attempt to
> quantify the bias imparted by nonblinding
> of trial participants ?
>
> please forward any details / thoughts to me
> directly and i'll return any replies to the
> list in a fortnight or so
>
> many thanks in advance
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rob manning
dphil student
dept of economics & related studies
university of york
york yo10 5dd
uk
phone: +44 (0) 1904 433790
fax: +44 (0) 1904 433759
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