Transcript CLINICAL REASONING

CLINICAL REASONING
IN GENERAL PRACTICE
Dr Charles Todd
OBJECTIVES
At the end of the session you should:
• Understand cognitive methods utilised in
making a diagnosis
• Recognise some of the special features that
apply in general practice
• Have a strengthened ability to reach an
accurate diagnosis in the general practice
consultation
• Understand how and why errors in
reasoning occur
KEY MESSAGE:
STOP & THINK!
Remember this antismoking slogan?
Plus message spray painted over it…
THINK FIRST MOST
DOCTORS
DON’T SMOKE
Smoke first –
Most doctors don’t
think!
WHY IMPORTANT?
Diagnostic errors:
i. Common: estimates 10-20%.
ii. Among medical errors are the second
leading cause of adverse effects (after
medication errors)
iii. Associated with high morbidity.
iv. The most common and most costly source
of malpractice payments (in UK & USA).
GENERAL PRACTICE
CONSULTATIONS
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Short
Enormously varied
Problems undifferentiated
Serious disease uncommon
Multiple tasks: the key one is to establish
the reasons for the patient’s attendance –
with new problems this means reaching a
diagnosis
MAKING A DIAGNOSIS
• Key competency for GPs
• Forms the basis for determining the patient’s
treatment, prognosis, etc
• Concerns moving “backwards” from the patient’s
complaints (the illness) to the disease (target
disorder)
• Important to consider physical, social and
psychological aspects
• The history is critical – examination and
investigations play a relatively small role
KAHNEMAN’S SYSTEMS
OF THINKING
• System 1 operates automatically and
quickly, with little effort
• System 2 involves effortful mental activity
• While most of the time system 1 is in
operation, system 2 can to some extent
overrule it
• We can “toggle” between the two
CLINICAL PROBLEM
SOLVING IN PRACTICE
What methods are used in reaching a
diagnosis?
1) Intuition
2) Hypothesis generation and testing
3) Follow a structured guideline or
algorithm
INTUITION
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Instant realisation that the presenting
signs and symptoms conform to an
already known pattern
Reflex rather than reflective
Applies where the presentations is very
familiar
“Pattern recognition”
Kahneman’s System 1
HYPOTHETICO-DEDUCTIVE
METHOD
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Analytical approach
Laboured, time-consuming
Kahneman’s System 2
Ideas are generated during the interview
about what the underlying problem is
• These “hypotheses” are then tested and
refined by further questions, examination
and investigations
MORE ON HYPOTHESES
• Hypotheses are “explanatory ideas” that are
increasingly refined through the
consultation
• The first are generated very early on in
history taking (within seconds)
• Usual strategy followed is to “prove” rather
than refute a particular hypothesis
• Used by clinicians of all types – more
experienced are better at it
GENERATING HYPOTHESES
Consider:
• Probability or likelihood of a given
condition in a specific setting
• Potential seriousness and
• Treatability
of any possible diagnosis – especially
with regard to the value of early
detection
WHEN THE GOING GETS
TOUGH
• Consider broad categories first, e.g. think
about what system is involved
• Keep an open mind
• Look for a unifying diagnosis
• Utilise checklists as aide-memoires
• Avoid fishing expeditions
• Listen to the patient and think!
CHECKLISTS
System-based
Pathological
Anatomical
Cardiovascular
Congenital
Skin
Respiratory
Acquired
Muscle
Gastrointestinal
- Traumatic
Bone
Genitourinary
- Infective
Pleura
Neurological
- Inflammatory Lungs
Psychological
- Metabolic
etc
Heart
etc
etc
SOURCES OF ERROR AND BIAS
• Jumping to conclusions and fixing on them – being “blind”
to other ideas
• Basing diagnosis on recall of a similar case from the past
or novelty, rather than awareness of epidemiology in the
setting
• Continuing reference to existing and/or extension of
existing diagnostic label
• Unquestioning faith in diagnostic labels applied by others,
especially consultants
• Failure to reassess when things don’t fit with what is
expected
ERROR AND BIAS (ctd)
• Confirmation bias: focus on ruling in rather than
refuting a particular diagnosis (i.e. only seeking
evidence to confirm)
• Over-reliance on results of investigations
• “Colluding” with the patient who is asking for
reassurance
• Multiple doctors involved
 failure to see the bigger picture
• Emotional factors / denial
• Being too tired or rushed
• Lack of knowledge and experience
EXAMPLES FROM PRIMARY
CARE SIGNIFICANT EVENTS
Presentation
Initial diagnosis
Eventual diagnosis
Reason for error
60 yr old rectal
bleeding
Haemorrhoids
Rectal cancer
Inexperience
Failure to follow
guidelines
2 yr old unwell
with fever,
unusual
blanching rash
Viral infection
Meningococcal
septicaemia
“Blindness” and
collusion
40 yr old obese
type 2 DM with
severe recurrent
vertigo
Labyrinthitis
Cerebellar stroke
Multiple doctors
Failure to reassess
COMMUNICATION SKILLS
FOR BETTER DIAGNOSIS
• Listen – and show it
• Don’t interrupt (“the golden minute”)
• Ask open-ended questions first, then more
directed ones
• Be receptive to all verbal and non-verbal
cues
• Summarise and check
• Be open to the patient’s perspective (ICE)
SPECIAL CONSIDERATIONS
IN GENERAL PRACTICE
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Be pragmatic and action oriented
Use time judiciously
Don’t trust specialists uncritically
Learn to live with uncertainty
Manage risk
Identify and respond to the patient’s ideas
about what is wrong
USE OF CLINICAL EPIDEMIOLOGY
TO IMPROVE DIAGNOSTIC
ACCURACY
• Statistical methods are underutilised in
reaching a diagnosis
• Estimate initial probability of disease
(prevalence in the setting)
• Know specificity and sensitivity of
diagnostic tests
• Refine probability based on strength of
evidence (“likelihood ratio”)
FINAL TIPS
• Generate more than one possible diagnositic
idea
• Think of the worst thing this could be
• Don’t just focus on presenting symptoms:
review recent consultations and look at bigger
picture
• Always be ready to reconsider or ask a
colleague
• Listen to your gut, but
• Never abandon your critical faculties
READING
Sackett D, Haynes et al. Clinical Epidemiology. A Basic
Science for Clinical Medicine. Little Brown
Elstein A, Schwarz A. Clinical problem solving and
diagnostic decision making... BMJ 2002; 324: 729-732
http://healthland.time.com/2013/04/24/diagnostic-errors-aremore-common-and-harmful-for-patients/
Scott I. Errors in clinical reasoning: causes and remedial
strategies. BMJ 2009; 339: 22-25
Fraser R. Clinical Method: a general practice approach.
Butterworth Heinemann.
Kahneman D. Thinking, Fast and Slow. Penguin, 2012