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Doctors May Guess Your Diagnosis and Why They May Be Wrong
This thread is all about heuristic clinical reasoning which
means a doctor's mental shortcuts to come to a diagnosis. Heuristic is defined
in Wikipedia as:
Heuristic (/hjʉˈrɪstɨk/; Greek:
"Εὑρίσκω", "find" or "discover") refers to
experience-based techniques for problem solving, learning, and discovery that
give a solution which is not guaranteed to be optimal. Where the exhaustive
search is impractical, heuristic methods are used to speed up the process of
finding a satisfactory solution via mental shortcuts to ease the cognitive load
of making a decision. Examples of this method include using a rule of
thumb, an educated guess, an intuitive judgment, stereotyping, or common
precise terms, heuristics are strategies using readily accessible, though
loosely applicable, information to control problem
solving in human beings and machines.
In medical practice there may be many reasons which encourage
heuristic clinical reasoning such as emergent medical situations or general
lack of time for detailed history taking and examinations, lack of resources
including an important resource would be a patient who was able to give
a medical history or a knowledgeable surrogate. Another factor promoting such
reasoning is the expense or potential health hazard to the patient from a
procedure which would be appropriate for a definite diagnosis. Finally, physicians who are not fully educated in a
particular specialty may be unaware of all the different diagnoses which are
available to consider. Unfortunately, for some physicians heuristic reasoning
tends to become a relied upon habit.
Here is a list of categories and the description of each by
1. ANCHORING-Focusing on vivid, salient features in a
clinical presentation early in the diagnostic process and failing to adjust
this first impression later as more information becomes available.
2. ASCERNMENT BIAS-When thinking is unduly influenced by
prior expectations (e.g. stereotyping or gender-bias).
3. AVAILABILITY-Options appear more likely when they are
readily brought to mind (e.g. a subacrachnoid hemorrhage diagnosis is given
more consideration on the differential for headache if it was seen in a case a
4. COMMISSION BIAS-The idea that something always needs to be
done to the patient instead of letting things take their course--more common in
confident physicians; things get done that were unnecessary.
5. CONFIRMATION BIAS-Looking for things to support your
diagnosis/hypothesis rather than looking for disconfirming evidence (which is
usually a more effective strategy).
6. CONTRAST EFFECT-When interpretation of a particular case
is influenced by adjacent cases--even though they are independent of each
7. DIAGNOSES MOMENTUM-When diagnoses gather momentum without
8. FUNDAMENTAL ATTRIBUTION ERROR- Judging and blaming particular
patients (e.g. obese, borderline personality disorder, addicted patients) for
their illnesses by focusing on their disposition (character, personality,
intelligence) rather than considering their situational circumstances
(socio-economic, upbringing, history of physical/sexual abuse).
9. HINDSIGHT BIAS- Learning from past experience is
hindsight. However hindsight bias occurs when, knowing the outcome, people
either make themselves look good or look bad, thereby distorting any chance of
10. OMISSION BIAS- The tendency toward inaction and
non-intervention. Error arises from
things not getting done that should have been done.
11. OVERCONFIDENCE-The general belief that we are better than
we really are--a misplaced belief that affects one's thoughts and actions.
12. PLAYING THE ODDS also known as FREQUENCY GAMBLING- is the
tendency in equivocal or ambiguous situations to opt for a benign diagnosis on
the basis that it is significant more likely than a serious one.
13. PREMATURE CLOSURE-Shutting off thinking before there is
sufficient evidence to suggest a particular diagnosis--when the diagnosis is
made the thinking stops.
14. REPRESENTATIVENESS RESTRAINT- We tend to look for
prototypical manifestations of disease--atypical presentations are more likely
to get missed.
15. SEARCH SATISFICING- reflects the universal tendency to
call off a search once something is found. Co-morbidities, second foreign
bodies, other fractures and co-ingestants in poisoning all might be missed.
16. VISCERAL BIAS- when emotions overly intrude into
decision-making. Countertransference may
result in feeling unduly negative or positive toward patients leading to
suboptimal decisions regarding diagnosis and management.
17. YIN-YANG OUT-The outlook that once patients have been
worked up the Yin-Yang further effort
will be futile.
18. ZEBRA RETREAT- Backing away from a rare diagnosis for
reasons other than it being rare: thinking that you will attract a reputation
of being esoteric, unrealistic or a
wastrel of resources or time.
19. TRIAGE CUEING- deals with Emergency Room triage: the
tendency to inherit the abbreviated thinking that occurred at triage
(patients seen in the minor area are
considered as only having minor complaints).
BLIND SPOT BIAS, a general belief that people have that they
are less susceptible to bias than others.
As you see, there can be many ways that heuristic clinical
reasoning can go wrong. And yet, doctors
will use this reasoning as part of the beginning to form a diagnosis when rushed or a diagnosis still
not firmly established at the time that some prompt treatment for physical support is
critical. But the "guess" has the many limitations as noted
above. So what is most important is that
all doctors should be aware that they are at the time practicing heuristic
reasoning and should know the details of what potential errors of reasoning can
occur by such use and thus use with caution.
Have you ever heard your doctor tell you: "I am just
guessing that you have..."? And how did or would you respond? ..Maurice.
Graphic: From Google Images-Alfred Nobel (1833-1896)