:-----Mensaje original-----
:De: [log in to unmask]
:[mailto:[log in to unmask]]En nombre de
:Djulbegovic, Benjamin
:Enviado el: martes 11 de julio de 2000 15:00
:Para: 'Evidence-based discussion group'
:Asunto: Randomized vs. Non-randomized trials.empirically an unanswerable
:question
:In my opinion, the question of hierarchy of medical evidence represents a
:core issue of EBM movement and if indeed assumption that "not all evidence
:is created equal" is not accepted then there is not much left of the EBM
:paradigm.
Indeed, hierachy of evidence is a "movement" core issue.
:Current, hierarchy of
:evidence is
:NORMATIVELY derived, and reflects belief in supremacy of
:experimental method...
No. Its "evidence based" and thus empirical. Not easy to quantify, specially
"post facto" but not a unsurmountable o unthinkable limitation.
:As postmodernists would say real life
:defies the precision of normative, mathematically ordained world; the truth
:is elusive and subjective. In deciding what works and what doesn't
:should we
:then add a "value factor" to each form of scientific evidence? Or,
:hierarchy...
No. We are commited to seek "truth", and the core issue, if I am getting
your point right, is an issue of validity. In the NEJM observational vs
randomized is on bias control. Individual study validity considerations are
not alien to EBM, and the NEJM should be a wellcome reminder.
The beauty of EMB seen also through postmodern eyes is that you cannot avoid
being conscious or else confortably ingnoring the firmness of the ground
supporting the different options available in the decisionmakin within a
specific clinical encounter
:Could it be that the current hierarchy of evidence is just not sufficiently
:good enough or that ranking of evidence is not a feasible exercise to begin
:with?
:
As "one size fits all" type of dress vs tailor made one, or fastfood vs
homecooking, there is a difference between a generic scale versus yourself
doing the ranking of all studies one by one. The latter is resource- and
timeconsuming, and is the reason for having frecuently updated CAT's or even
for initiatives like government based, or proffesional Technology Assesment
initiatives, where the individual component challenges to valididy are
sistematically and thoroughly revised.
:These are crucial issues to whole idea of EBM, and it would be interesting
:to hear opinions from the members of the group
:
Thank you Benjamin for raising such an important issue.
It has thee merit of reminding on the need to discern between intelligent
practice of medicine vs cookbook or "industrial" one...
Jordi M. Gol Freixa MD
Agencia de Evaluación de Tecnologías Sanitarias
Instituto de Salud "Carlos III"
Ministerio de Sanidad
www.isciii.es
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