Cognitive Heuristics
Vignesh Narayanan, M.D
Denver Health Medical Center
“An expert is a person who has made all the
mistakes that can be made in a very narrow field”
- Neils Bohr
err
I think, therefore I am
- Descartes,1664
Heuristics- definition


‘Heuriskein’ – ‘to find’ or ‘discover’ (Greek)

subconscious rules of thumb

shortcuts in diagnostic reasoning
‘Eureka’ has the same origin
Case presentation

63 y.o female, could speak only Spanish

CC: chest pain, progressive dyspnea

HPI: Chest pain X 2 wks
 sub-sternal, recurrent, episodic
 non-radiating, non-exertional
 worsened by deep inspiration

Other complaints:
 progressive dyspnea x 2 wks
 non-productive cough, no orthopnea/PND
 subjective fevers – 3 wks
Case: continued

Past medical history
 diabetic, hypertensive
 osteomyelitis of L- 5th toe, amputation 2 mos PTA
 CHF: diastolic dysfunction, EF > 55%
 CKD: baseline creatinine of 1.6

Medications:
 lasix 120 mg BID, stopped 2 wks PTA
 metoprolol, amlodipine, hydralazine, rosuvastatin
 glargine & lispro
Case: continued

Surgeries
 amputation of L- 5th toe 2 mo PTA

Social history
 life long non-smoker, no alcohol

Family history
 mom with ‘heart problems’ NOS
 ten children

No allergies
Case: continued

Examination
 vitals: T:36, HR: 71, BP: 100/75, RR: 18
 normal JVP, normal cardiac exam
 bilateral diffuse crackles
 no edema of ext’s
 left 5th toe amputation site- normal

Labs/data
 Na: 126, BUN: 48, Creat: 1.9
 WBC: 11K, TnI: normal
 CxR: consistent with pulmonary edema
 EKG: NSR, no new changes
Case: initial A & P

Chest pain/cough

pleuritic in nature

c/w acute bronchitis- p.o azithromycin

SOB: Pulmonary edema unlikely given nl JVP

“dry” by labs- hyponatremia, BUN/creat ratio

? ILD- check PFT’s, HRCT, pulmonology consult

Acute on chronic renal failure: Likely volume depletion

check UA, U.lytes, U.Osm

substantiated by hyponatremia – IVF 500 ml NS

Subjective fevers, mild leukocytosis: occult infection ?

recent osteomyelitis- amputation site- well healed

check UA, ESR, CRP
Case: hospital day # 1






Improvement in symptoms
Complaint: pain over left temple & behind ear
Exam:
 HR: 81, BP: 105/60, RR: 18, Sat: 92% 2L NC
 B/L diffuse crackles
Labs:
 Na 135, creat 1.8, WBC: 11K
 CRP: 170, ESR: 110
Assessment:
 dyspnea, hypoxia, diffuse crackles- ? ILD
 pain L temple, elevated ESR, CRP- ? Temporal arteritis/PMR
Plan:
 HRCT, PFT’s, rheumatology consult, echo
Case: hospital day # 2






More pain L temple/behind ear
More SOB than admit
Exam:

nl vitals, 93% 4L NC

b/l diffuse crackles
Other labs

UA: 21-50 WBC
PFT:

restrictive lung defect
HRCT:

no ILD

b/l pleural & moderate
pericardial effusions

coronary LAD calcification

Assessment/plan:

pleuro-pericardial effusions,
temple pain, high ESR,
CRP

suspect CVD

echo for dyspnea
Case: hospital day # 2

Rheumatology:
 no evidence of CVD by history or exam
 alternate etiology for high CRP/ESR- r/o infection
 tap pleural effusion, check labs

Pulmonology:
 HRCT, PFT abnormalities likely due to CHF/pulmonary edema
 diuresce with IV lasix
Remaining hospitalization

Infection W.U
 sinus CT: nl mastoid
 foot X ray- no OM

Treated for UTI

Dyspnea, O2 sat
 much better with lasix

Echo:


global hypokinesis
EF lower than 2 mos ago

Discharged on day 4
 Diastolic failure with
pulmonary edema
 UTI
 Atypical chest pain
 Acute on CKD
2 days after discharge

Outside hospital
 chest pain, dyspnea

Cardiac arrest in ED

Coronary angiogram
 near total block of LAD
 PCI
 doing well
Summary
elderly woman with
Chest pain
investigated for
several diagnoses
(ILD, CVD, Infection)
discharged with
alternate diagnosis
(diastolic CHF)
eventually diagnosed
with different
disease (critical CAD)
Missed diagnosis
Cognitive Psychology (of diagnosis )
Diagnosis
Reason
Therapy
Make
Decisions
Formulate
Judgments
Why we take shortcuts
ER doctor
Tom Brady


Lack of time
Memory
 rationality is bounded
Lehrer. How We Decide. HMH Press; 2009
Simon HA. Annu Rev. Psychology 1990; 41:1-19
Heuristics: ‘Shortcuts’ in diagnostic reasoning
Pitfalls are
repetitive &
impalpable
Reduce time, deliberation
Wrong conclusions
Shortcuts in reasoning
Fever, cough,
chest pain =
Pneumonia
Acute PE
‘Availability’ heuristic

Does the English language have
more words that start with the letter ‘r’
(or)
more words that have the letter ‘r’ in the third
position?
Tversky & Kahneman- Cognitive Psychology. 1973;5: 207-32
‘Availability’ Heuristic

Ease of recalling past cases
 likelihood judged by easily ‘available’ past eg’s

More convenient than collecting & memorizing
probabilities
Common diagnoses
are common
High CRP =
infection,
inflammation
Un-common diagnoses
not considered
High CRP =
predicts
CAD risks
‘Anchoring’ Heuristic
First impression - Best impression?
Easier than constantly
re-integrating evidence
Anchored on lab
values
(Hyponatremia, CRP)
Lack of one finding
(Elevated JVP)
Failure to check for
disconfirming evidence
‘Framing’ Heuristic
atypical CP, serositis
+
suspected ILD ,temple pain
+
elevated ESR, CRP
Collagen vascular Dz
DM, recent toe OM
+
bronchitis
+
mastoid pain: ? sinusitis
+
abnormal UA, high CRP
Infectious process
atypical angina, CAD risks
+
new decrease in EF, pulm edema
+
calcified LAD, high CRP
Serious CAD
Other heuristics, biases

‘Blind Obedience’:
 Technology


Superior authority


PFT “restrictive lung disease”
rheumatology- “consider infection”
‘Premature Closure’
 reluctance to pursue alternate diagnoses
 using evidence that seems confirmatory
 dismissing evidence that is contradictory
Avoiding heuristic biases
Problems to acknowledge

Many clinicians are unaware of their error*
 too distal in time or place
 lack of effective feedback

Overconfidence**
 declining autopsy rates (<10%)

Sense of pessimism in the literature
 “cognitive errors are high hanging fruits”
 “the search for zero error rates is doomed from the
start”
*Redelmeier- Ann Intern Med 2005;142:115-120
** Berner & Graber- Am J Med 2008;121:S2-S23
Strategies to minimize heuristic bias
Diagnostic error
Normative
approach
- pay more attention
- be thorough
- practice more
- don’t forget this next time
Cognitive psychology
approach
- awareness about
heuristic biases
- adding safeguards
against reflexive decision
making
Strategies to minimize heuristic bias

Gordian Knot
2 core strategies

Metacognition

Cognitive forcing
Strategy 1: Meta-cognitive training

Meta-cognition: “thinking about thinking”
“If at first the idea does not sound absurd, then there is no hope for it ”
- Albert Einstein

2 processes occurring simultaneously
 awareness of learning process to monitor progress
 adaptive strategies based on progress

Requires the clinician to
 stand apart from his/her own thinking & observe it
 recognize opportunities for intervention
Croskerry- Ann Emerg Med. 2003; 41: 1
Metacognition
Crystal ball experience
This plan is proven faulty
& does not work. Please
devise an alternate plan



Promotes open minded thinking
Helps to ‘step back’ and rethink
Ensures multiple possibilities are considered
Graber et al. Acad Med. 2002;77(10):981-92
Mitchell DJ- J Behav Decis Making. 1989;2:25-38
Strategy 2: Cognitive forcing
“Deliberate, conscious selection of a particular
strategy in a specific situation to optimize
decision making and avoid error”
Croskerry- Ann Emerg Med. 2003; 41: 1
Some ‘pills’ for our cognitive ‘ills’
Clinical shortcut
Corrective strategy
‘Availability’
Easy recall
Decrease reliance on memory
verify facts - read more
‘Anchoring’
1st impression
Reconsider in light of new data,
seek 2nd opinions
‘Framing’
Subtle wording
Play devil’s advocate
‘Blind obedience’
Deference to authority
Re-confirm human work/ test accuracy
‘Premature Closure’
Narrow belief
“What is the diagnosis that I do not want to
miss?”
Reidelmeier D. Ann Intern Med 2005; 142(2): 115-120
Croskerry P. Acad. Med 2003; 78: 775-780
Experts might feel like…
Summary

Cognitive short-cuts:

due to lack of time & bounded rationality

Double edged swords

Overcome by

metacognition & cognitive forcing
Thanks!
“Too often the shortcut, the line of least resistance, is
responsible for evanescent and unsatisfactory success”
- Louis Binstock
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