

This is what happens when too few MDs understand Bayesian inference - leot
http://www.nytimes.com/2011/10/07/health/07prostate.html

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carbocation
Would you mind editorializing in a comment rather than in the title?

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leot
Extra true information can only ever be a good thing if handled properly.

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drcode
Does anyone know if this observation has a name? There must be an official
name for this logical fact.

I ask because I'm an MD and made this point during a conversation with another
MD a while ago and the other guy looked at me like I was a fool to believe
this. He responded along the lines of "But a study has shown that people given
test X for disease Y do worse than people not given the test."

To him, this was a proof by negation, which of course it is not.

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leot
I can't think of one. Hopefully there is -- if not, it needs coining.

Your friend is wrong, though, if this extra information was "cheap" to obtain
(caused no harm to the patient and was low cost).

The argument used is that extra testing causes needless treatment, in the end
causing more harm than good (we'll call a treatment "costly" if it has a large
opportunity cost or causes harm).

For the MD you mentioned, the test could cause people to "do worse" because
either the test is harmful or the MD's use of its results is harmful. If the
test is harmful, then it probably shouldn't be administered unless other
evidence suggests it's necessary. If it's the MD's use fo the results that
causes the harm, then it just means the MD should use the results differently.

If the problem is the MD's reasoning, then one possible source of error is in
giving a much higher prior probability to the patient's having the disease, or
an ignorance of what, e.g., a "bad" result actually implies.

In the case of the PSA test, it looks like the fee-for-service model is
leading many doctors to ignore the relationship between a high PSA result and
the probability of the patient's dying from prostate cancer, in addition to
ignoring the harm that will be caused by performing a biopsy or by any further
treatment.

Perhaps more malpractice lawsuits that focus on needless treatment would put a
dent in this problem ...

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drcode
In my opinion, 100 years from now, our ancestors will view the lack of basic
statistics literacy as one of the primary failings of our present society.

