From: hrubin@pop.stat.purdue.edu (Herman Rubin)
Newsgroups: sci.med
Subject: Re: Questions for MDs
Date: 29 Jul 92 14:15:36 GMT
Organization: Purdue University Statistics Department


In article <15575@ucdavis.ucdavis.edu> fzjaffe@hamlet.ucdavis.edu (Rory Jaffe) writes:
>In article <55267@mentor.cc.purdue.edu> hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
|>In article <15524@ucdavis.ucdavis.edu> fzjaffe@othello.ucdavis.edu (Rory Jaffe) writes:
|>>We also have essentially stopped using one drug for adults (halothane)
|>>because of this.  Severe halothane hepatitis probably has an incidence
|>>of 1:100,000 adult anesthetics with halothane (give or take).  But
|>>anyone who turns yellow after an operation can get the label tacked on
|>>by someone, and then sues.  It's hard to explain to a jury that the
|>>hemodynamic effects of halothane vs. isoflurane may cause you to prefer
|>>the former in patients with coronary artery disease.  The risk-benefit
|>>argument doesn't seem to go over well.  For comparison, the incidence of
|>>fatal reaction to penicillin is also about 1:100,000. 

|>This is an excellent example of the problem with the practice of medicine.
|>If the medical crew makes the decision, they should be stuck with the
|>consequences.  On the other hand, if the patient is given the full
|>information, and makes an informed decision, only wilful fraud or
|>clear incompetence, as determined by a review board which is composed
|>of good physicians and pathologists who hate incompetence, but respect
|>honest differences, should be actionable.

>Stuck with the consequences?  Give me the hepatitis?  How about if, as a
>result of NOT choosing halothane, the patient gets a heart attack?  Sue
>me then also?  You want me to give the patient a full lecture on the
>risks/benefits of the various alternatives, and then have the patient
>make the decision.  This can be done for the major components of the
>decisions (e.g. to operate or not, whether to have general or regional
>anesthesia), but is extraordinarily impractical for the thousands of
>minuteae involved.  It takes years to educate a resident about these
>topics.  And internists (at least judging from their consult notes)
>generally never understand the various nuances involved in anesthesia (I
>guess that's because we're non-cognitive & they're cognitive
>practitioners). Actually cause-effect for both hepatitis and heart
>attack as I'm discussing here is not this simple; I'm using it for
>discussion's sake.  We're always working with odds, and the effect of
>the choices I've outlined here is slight, both on the risk of hepatitis
>and the risk of heart attack.

>By the way, what I didn't emphasize in my original note was that the
>yellow person usually is yellow because of some other reason.
>Post-transfusion and non-specific hepatitis are much more common than
>halothane hepatitis.  Causation seems to be unimportant, as long as one
>of the defendants gave something that possibly did it.  Awards are never
>adjusted by the probability of culpability.  The other thing, which I
>did emphasize in my note, is that 1:100,000 is generally considered a
>nil risk--otherwise we'd be giving informed consent for penicillin
>tablets.

Which you should!  If you think that the use of probability is that 
simple, I assure you that you are greatly mistaken.  No, I do not 
expect doctors, or anyone else, to be able to handle small probabilities
without calculation.  I am always working with probabilities, and I am
rather quick with mental calculation, and I would not attempt it.  A
chance of 1:100 of getting a stomach ache may (?) be considered a nil risk,
but not a chance of 1:100,000 of getting a fatal condition.  The question
is not the probability per se, but the loss-weighted probability.  And it
must be the patient's loss, except in the case of contagion or something
similar. 

One of the things one learns in looking at even slightly complicated
models, in mathematics and elsewhere, is that the "obvious" result of
the action often results in consequences quite different from the 
intended ones.  It is possible that a direct treatment of a condition
can cause long-term damage.  The medical profession has to learn to
consider realistic models, and to understand what needs to be used to
make decisions, and to communicate them.  Until the pracititioners of
medicine can understand these problems, they will be unable to present
choices for informed consent to their patients, nor argue them in the
courts.

BTW, assuming that penicillin tablets are given to 10,000,000 people in
a year, which is probably conservative, a chance of 1:100,000 would give
100 people affected.  And if the 1:100,000 is an overall average, counting
those who have been given penicillin more than once, the correct odds for
someone who has not been given penicillin are much higher.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: (317)494-6054
hrubin@pop.stat.purdue.edu (Internet, bitnet)  
{purdue,pur-ee}!pop.stat!hrubin(UUCP)
Newsgroups: sci.med