Terry Shaneyfelt wrote:
> Does any one have a good example of a fairly flawed therapy article for a
> course that I teach in EBM. Seems most of the articles I find arent too badly
> designed. Students always want to see some bad articles to critique.
The cynic in me says that you need to spend more time reading journal
articles.
But I'm not much of cynic actually, and if anything I would discourage
this activity.
I've always disliked the concept of finding an article that you can
trash. I think it creates a sense of cynicism in students and also
develops the false impression that critical appraisal means literally
being critical of everything you see. It also encourage black and white
thinking while most studies are on a continuum of the persuasiveness of
the evidence.
I've heard the comment made more than once along the lines of read the
methods section first and if you see something wrong then stop reading
the article. I would disagree with this advice. I would say that you
still read the methods section first, but only to assess the degree of
persuasiveness that this article is likely to have. Then look at the
results. Finally, see if there is any corroborating evidence (plausible
mechanism, replication of an early result, strong effect, dose-response
pattern, specificity of effect, and so forth). Conflicts of interest
factor in here also. If the evidence is highly objective, then it
doesn't matter if there was pharmaceutical money involved. But a
borderline finding becomes that much less persuasive when there is such
a conflict.
I do mention a few bad studies in my book (Statistical Evidence in
Medical Trials). For example, there is the famous study by Linus Pauling
about vitamin C that prospectively evaluated patients with terminal
cancer on vitamin C but used for a control group patients selected from
a death certificate database.
Supplemental ascorbate in the supportive treatment of cancer:
prolongation of survival times in terminal human cancer. Ewan Cameron,
Linus Pauling. Proc Natl Acad Sci USA 1976: 73(10); 3685-89.
www.pubmedcentral.nih.gov/picrender.fcgi?artid=431183&blobtype=pdf
But those examples are to illustrate a specific lesson. I would be
uncomfortable asking students to find the flaw in these studies.
You should critique studies that are representative of what students
will encounter in the real world. If those articles are mostly well
designed, then so be it.
--
Steve Simon, Standard Disclaimer.
My new website, www.pmean.com, is up and running!
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