In message <BFBF2B9D5420D4118089009027FC77890136F95D@N-
Mail.moffitt.usf.edu>, Djulbegovic, Benjamin <[log in to unmask]>
writes
> In this article, the authors (who happened to be the
>leaders in the field) re-confirmed that the major contribution of EBM
>movement to contemporary medicine is the idea there exists a "hierarchy of
>medical evidence".
I agree that this is A major contribution of EBM but THE major
contribution?
A hierarchy is a useful tool as one part of the assessment of internal
validity of experimental or observational studies. However it really has
little to contribute to judgements about applicability which is just as
much a concern of clinicians.
Hierarchies of evidence seem to work well enough for quantitative (or
post-positivist if you prefer) research methods but completely fall down
in the assessment of qualitative research whose validity depends not
only upon the research methods and how well these were carried out, but
on the research question and its context.
The lack of understanding of how evidence can be used to inform clinical
decisions with individual patients is one of EBM's main weaknesses. We
all "know" that good EBM clinicians are also good communicators with
their patients, but we don't understand exactly how they do it, and it's
not one of the things that we usually concentrate on at EBM workshops,
for example. This important question could not be studied by
quantitative methods and therefore evidence about it would not fit into
a hierarchy. Does this mean that it is less important than a meta-
analysis of the effectiveness of statins in cardiovascular risk
reduction post MI? Suppose our post-MI patient misunderstands our
explanation of why we are giving him several different pills to take
home and only takes them when he feels ill, or doesn't collect his
repeat prescription from his GP? What use is the meta-analysis to him
then?
For my money, the major contributions of EBM are:
1) reinforcing the right and obligation to question extablished practice
2) demonstrating the applicability of epidemiological tools to everyday
clinical practice
3) making the uncertainties of clinical practice explicit and
quantifiable
Toby
--
Toby Lipman
General practitioner, Newcastle upon Tyne
Northern and Yorkshire research training fellow
Tel 0191-2811060 (home), 0191-2437000 (surgery)
Northern and Yorkshire Evidence-Based Practice Workshops
http://www.eb-practice.fsnet.co.uk/
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