From: hrubin@pop.stat.purdue.edu (Herman Rubin)
Subject: Re: Bashing, truth, etc.
Keywords: clinical judgement, multi-variant analysis, factors  
Organization: Purdue University Statistics Department
Date: Thu, 24 Dec 1992 19:14:25 GMT

In article <1992Dec22.195844.22294@pegasus.com> tas@pegasus.com (Len Howard) writes:
>In article <BzM7Gs.8sM@mentor.cc.purdue.edu> hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
>
>[prior discussion of folk & scientific medicine deleted]
>>
>>As to the first issue, I am afraid you misunderstand both what I said and
>>also what is involved in "scientific" medicine.  I am putting on my 
>>professional hat here.  The problem in any form of inference is that
>>of decision making under uncertainty.  Now this problem, even simplified
>>to the standpoint of a self-consistent person with infinite computing power,
>>has only been reasonably treated in this century, and from the most general
>>statement of the problem, I am credited with the first general result (1948).
>>But even in the last century, the idea that a simplified model could be
>>CORRECT, as distinct for APPROPRIATE FOR USE, came to be recognized.  It
>>is never the case that the proposed action has NO effect, so that the usual
>>testing is just plain wrong.  And in the cases in the biological, social,
>>and psychological sciences, where the accuracy of the simplified theory is
>>much worse than that of the data, this problem gets very difficult, and 
>>even relatively simple problems show unexpected complications.  
>[effect of Vit C deleted to save space. Main point follows] >
>>individuals, how does it interact with other things, etc.  The problem is
>>not an easy one which can be handled with a simple statistical package.
>>In addition, in quite reasonable problems, such as can be encountered in
>>everyday medical practice, the resolution of the problems with the available
>>information may involve computations, the results of which can be very much
>>counterintuitive.

>>We must use methods appropriate to the information available, not just
>>those appropriate to the simpler problems of physics and chemistry.  And,
>>in addition, we must take into account that "one man's meat is another 
>>man's poison", and that individual preferences, even for supposedly 
>>identical individuals, differ enough to affect the appropriate action.

>Dr Ruben, I would like to in a sense agree with your thesis but in
>addition expand a bit on the decision making process I see in my own
>practice of medicine.  After reading your post, I tried to analyze how
>I make the treatment decision in a particular case. To wit...
>    The decision to recommend one particular course of treatment has
>several variables:
>a. The underlying medical education of the physician.  What sort of
>philosophical base is present.  What was the thrust of the education
>provided by the particular medical school, i.e. was it pragmatic,
>developing general practitioners, or was it theoretical, intending to
>produce research physicians?  How many years ago was the physician in
>medical school?

>b. Does the physician keep up with the medical literature?  No one
>person can accumulate enough experience to personally have treated
>enough patients in many uncommon conditions in order to develop a
>significant sample to make a valid treatment recommendation.  "Fad
>treatments" are the result of depending on one's own limited
>experience.  Using the medical literature, while recognizing the bias
>of the submitter, will enable the physician to make a decision based
>on a large enough sample to have some validity.

There is a saying,

	Any fool can learn from his own experience.
	The wise man learns from the experience of others.

I do not agree that the first sentence is correct, but the second certainly
is.

>c.  What is the experience of the physician.  Medicine changes rapidly
>in the last 40 years, and many physician new to the practice have
>never done some of the procedures that were common in the 50s, and
>still provide advantages today.  Likewise, there are many new
>procedures that require the older physician to keep up with current
>methodology and learn the new techniques as they achieve validity.

The problem is not just with procedures; the more important problem is
diagnosis.  If a problem is not routine, literature searches and
consultation are important.  

>d.  What is the mode of practice of the physician?  Is he one who is
>quick to jump to the newest treatment, or one who will stick with
>proven methods until a significant amount of experience is published
>in the literature.  Is the physician practicing in a large group,
>where the consensual mode is the way of all, or in private practice
>where the individual is free to follow his own dictates without
>constraint.

The physician has the responsibility of providing the information in such
a way that the patient can make the relevant decision.  This is, unfortunately,
rarely done.

>e.  Finally, what is the patient like?  There is a quantum difference
>between discussing treatment options with a professor of Biochemistry
>at the local medical school and a young unmarried woman who dropped
>out of high school because she got pregnant at age 16.  In the former,
>as position of collegiality may be productive, while in the latter a
>paternalistic, benevolent attitude may be the only option.  And what
>is her response to the information provided?  Is it necessary to couch
>counseling in non-threatening terms to a person who is skittish, or
>can one go into all the options with a calm, thoughtful mature
>individual?

In my experience with many physicians in several places, all with major
universities at which I have been a faculty member or a visiting faculty
member, I have never had much of a discussion of alternatives.  If the
patient is not capable of intelligent decision-making, at least an
ombudsman not representing the physician should be required, as it is
in most places for the informed consent for surgery.

But the problem is not just that of treatment for an "established" 
condition; it is even more present at the diagnosis stage.  Very few
physicians will continue to search for other important non-optimal
physiological conditions if conditions have been identified which 
explain much of the problem.  Instead of thinking in terms of one
or two chronic conditions, it should be in terms of a half-dozen 
to a dozen.  This is not being done now, nor do I see anything but
a move away from this.

>The sum total of all these factors, I believe, goes into making up
>what we call clinical judgement, and what you, I think, refered to as
>intuitive decision making.  I submit that trying to enter all these
>factors into a statistical program may produce a decision which may
>appear globally correct, but may in fact not be the best decision for
>that particular patient.  There is a non-quantifiable sensitivity to
>the patient that the experienced physician develops over the years
>that takes a part in each medical decision.  I really don't think this
>can be programmed into any objective decision-making program, but you
>are the expert in that field <g>.

On the contrary, I see no other way to do it except by at least approximate
quantification and careful attempts at computation.  I am choosing my words
carefully here, because any "correct" way to do it would require those 
carrying out the process to be completely self-consistent and to have 
infinite computing power, or at least far more than the universe allows.
But this type of approximation is necessary in other fields as well.
It is the careful quantification of a difficult problem which allows
one to obtain reasonable solutions.

The computational problem is every bit as difficult as I have stated
it, and I am not exaggerating about careful computation showing that
the intuitively obvious solution is frequently very poor.

>>I agree fully with your last thr [sorry for screwing up the format] er
>ee sentences, but I have yet to encounter
>>a physician who does this.  I suspect that even those who try fail because
>>of their lack of familiarity with the range of possible actions, of which
>>much must be laid to the medical school training, and the training of
>>interns and residents.

I have not seen it done, either.  Part of it is due to the almost total
lack of familiarity with this type of approach; it is likely to take
going over a few examples where the "intuitive" solution is far from
optimal to convince people of the fact.  I even doubt if many of those
in the field of medicine are reasonably acquainted with this way of
thinking.  But when the problem is to balance a variety of consequences,
and necessary ignorance (the physician does not KNOW what the patient's
condition is; there is a considerable amount of doubt at all times),
it is necessary to calculate.

>This is the place where how the decision is made depends on all the
>factors I enumerated.  I think we can go too far in invilving the
>patient in the final decision.  By this I mean that I see some younger
>physicians today unwilling to make a medical recommendation, rather
>presenting the options and letting the patient choose the course.  I
>think this is just as wrong as not telling the patient anything and
>making your own decision total for them.  The patient, unless trained
>as a physician, with experience and background equal to your own, can
>only express a preference as to how she perceives what you tell her.
>The physician who makes no recommendation is copping out on his
>responsibility as a professional.  If I were attemting to set up a
>sampling method to analyze patient's behavior impacting on results of
>medical treatment, and came to you in consultation, I would expect you
>to make a recommendation.  If all you did was try to teach me some
>principles of statistical analysis and tell me to make my own
>decision, I would feel you had not helped me much.  I would want your
>recommendation as to how I should set up my model.  That's what I come
>to you for, to benifit from your expertise and experience.

This is, unfortunately, what too many expect of statisticians, and it is,
also unfortunately, what too many accommodate.  As a statistician, I am
not entitled to make the assumptions on which the analysis depends.  I
may point out that some assumptions have little importance.  It would be
like your telling patients which of several life styles would make them
happiest; this is not your prerogative, except to explain enough about
consequences of the life styles that they can make intelligent decisions.

Now if you came to me, I would question you to find out what your assumptions
happen to be.  And I would help in assessing them.  But the model is not for
the statistician to make, and using a model contrary to the subject field
IS quite apt to result in poor action on the basis of it.

Now I would not expect you to be able to see all of the consequences of your
assumptions, and I may even miss some important ones.  Nor would I expect
you to be able to carry out the analysis, nor design the experiments, nor
even to gather the data.  But it would be YOUR model, with YOUR assumptions,
which should be analyzed.  There is far too much of setting up incorrect
models which are easy to analyze going about.  Typically, the biggest part
of statistical consulting is getting the client to formulate the assumptions
precisely enough that mathematics can be used.  This is analogous to 
overcoming the patients' lack of medical knowledge by getting their 
input.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: (317)494-6054
hrubin@snap.stat.purdue.edu (Internet, bitnet)  
{purdue,pur-ee}!snap.stat!hrubin(UUCP)
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