Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

How do you feel about Evidence-Based Medicine? Part III


Continuing from Part I and Part II, examining some of the claims made by people who do not like EBM (Evidence-Based Medicine) even though they do not appear to have taken the time to find out what EBM is.

Here is one more of the claims made in the comments of Medscape‘s physician-only discussion of EBM (Evidence-Based Medicine) and SBM (Science-Based Medicine).[1]

I see EBM as a way of “dumbing down” medicine to allow NP’s to try to practice medicine[2]

Because, in the mind of this doctor, reading and understanding evidence takes less thought than making stuff up as we go along our merry way, ignoring what really works.

The opposition to EBM is often from the most superstitious people.

Why?

Because maintaining superstitions requires that we ignore evidence that the superstition is a bunch of nonsense.

Don’t say that it is quiet or slow, because some magical creature will cause something bad to happen to several people just to punish us for saying Voldemort.

This requires, in addition to the magical intervention of some unknown malicious creature, a lack of understanding of reversion to the mean.[3]

When it is slower than usual, unless something significant has changed, the volume of patients will return to the normal level. When it is busier than usual, unless something significant has changed, the volume of patients will return to the normal level. That is just the way that reversion to the mean works. It isn’t magic.

Daniel Kahneman explains reversion to the mean in his explanation o why praise does not appear to work, but criticism does. After either praise or criticism we should expect reversion to the mean. Less bad performance and less good performance are usually both examples of reversion to the mean, regardless of what we do.[4]

Skinner’s pigeons were similarly superstitious. If they spun around before their food was delivered, they thought that spinning caused the food to be delivered and would spin to try to get food delivered. We are not any better. We have lucky totems, or rituals, that are supposed to invoke magical powers, just as the pigeons try to invoke magical powers by standing on one leg, or tapping twice fast, pausing, then tapping once, or whatever else they associate with the outcome they want.
 


Image credit – the captions are mine.
 

We practice medicine the same way pigeons would practice medicine.

What do we remember doing just before we noticed our reward? In medicine, our reward is some sign that the patient might be improving. The patient does not need to actually get beet. seeming to start getting better, but not getting better is often perceived as a sign that we did not do enough of what we think we did, but not as a sign that what we did prevented the patient from getting better. Our bias is that we heal, so we tend not to think that we caused harm.

If we could patent spinning and tapping at a button, we would probably behave much more like the pigeons in the behavioral conditioning studies.

Evidence? No that doesn’t work. I base my treatment on superstition, just as if I were a pigeon!

I once gave X to a patient and he got better. X must have done it. X hasn’t worked as well as I would have liked, but I can only distort the truth so much with my biased memory.

Even the treatments that do have good evidence that they improve outcomes have dangerous side effects. All drugs do.

If the EBM treatments have dangerous side effects that we know about, how much more dangerous are the effects of the treatments we don’t know about?

We do not have good evidence of their actual effects, so how would we know?

Also read Dr. Crislip’s analysis of the same discussion.[5]

Footnotes:

[1] How do you feel about Evidence-Based Medicine?
Medscape
Article

[2] “How do you feel about Evidence-Based Medicine?”
Dr. Harriet Hall
May 29, 2012
Science-Based Medicine
Article

[3] Regression toward the mean
Wikipedia
Article

[4] Daniel Kahneman’s autobiography for the Nobel Prize
Nobelprize.org
Article

[5] Science, Evidence and Guidelines
Dr. Mark Crislip
June 15, 2012
Science-Based Medicine
Article

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