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Medical Errorand Cognitive Bias
Pat Croskerry MD, PhD
Canadian Society of Internal MedicineAnnual Meeting
Halifax, 2019
CSIM Annual Meeting 2019
Pat Croskerry: Medical Error and Cognitive Bias October 4 2019
The following presentation represents the views of the speakerat the time of the presentation. This information is meant foreducational purposes, and should not replace other sources
of information or your medical judgment.
Learning Objectives
1. Understand the dominant model of decision making – dual process theory2. Appreciate how cognitive biases may distort our decision making3. Appreciate how critical thinking and bias mitigation may improve clinical reasoning and decision making
Makary and Daniel, BMJ 2016
Data source: Xu et al, 2016 NVSS
(National Vital Statistics System)
Estimated number of preventable hospital deaths due to diagnostic
failure annually in the US
40,000 – 80,000
Leape, Berwick and Bates JAMA 2002
For the UK for 2018 this would translate to
9000 – 18,000
Preventable deaths due to diagnostic failure in hospitalized patients
Diagnostic failure is the biggest problem in
patient safety
Newman-Toker, 2017
Many physicians are reluctant to believe this
Diagnostic Failure
15%
Sources of Diagnostic Failure
Graber M, Gordon R, Franklin N. Reducing diagnostic errors in medicine: what’s the goal?
Acad Med. 2002
The Individual75%
The System25%
Kachalla et al, Annals of Emergency Medicine 2007
It varies by specialty
DermatologyRadiology (1-2%)Anatomic pathology
Internal medicineFamily medicine (~15%+)Emergency medicine
Diagnosis is the canary in the coal mine for decision failure
Legal outcome by critical incident
0
40
80
120
160
200
240
Perform Comm Diagnosis Admin Medication Conduct
CMPA Data : 347 legal actions closed 2005 - 2009
Number of patients
Legal outcome by critical incident
0
40
80
120
160
200
240
Perform Comm Diagnosis Admin Medication Conduct
CMPA Data : 347 legal actions closed 2005 - 2009
Legal outcome by critical incident
0
40
80
120
160
200
240
Perform Comm Diagnosis Admin Medication Conduct
CMPA Data : 347 legal actions closed 2005 - 2009
The complexity of diagnostic reasoning
Gender
Ethnicity
Perseverance
Mindfulness
Reflection
Age
Intellect ActiveOpen-minded
Culture Critical thinkingRationality
Adaptiveness
Experience
Experientiality
Need for cognition
PersonalityLogicality
Metacognition
BA
C
Fatigue Cognitive load
Sleep deprivation
Sleep debtStress
Affectivestate
Teamfactors
Lateral thinking
Religion
Knowledge
DSystem design
IT
Communication
Scheduling
ESymptoms Signs
Pathognomonicity
Co-morbidities
Progression
FPatient
Family
Friends
CaregiversOnset
Ergonomic factors
MimicsOther
patients
Understanding clinical decision making
Dual Process Theory
Decision Making
Intuitive (System 1)
Rational(System 2)
Fast Informal
SubjectiveContext-dependent
QualitativeFlexible
SlowFormal
ObjectiveContext-independent
QuantitativeRigourous
Dual Process Decision Making
Dual Process Decision Making
System 1: Automatic/streamlined System 2:Cautious/complex
Axial view of fMRI activation of the brain as a function of practice over 60 minutes
Hill and Schneider, 2006
A schematic model of how the systems work together
Pattern Recognition
Repetition
Executiveoverride
Irrationaloverride Calibration Diagnosis
PatientPresentation
RECOGNIZED
NOTRECOGNIZED
Type1
Processes
Type2
Processes
TPattern
Processor
95%95%
5%
“Getting” medicine is not easy
Decision making involves learning the basic patterns
COW
“Getting” medicine is not easy
“Getting” medicine is not easy
“Getting” medicine is not easy
The best calibrated decisions are described as
‘rational’ – they come from a blend of System 1 and
System 2 decisions
Being rational
The best possible decision given the available evidence and the prevailing conditions
Assuming you are well-slept, well-rested, well-fed, and can give the problem your undivided attention
And you are aware of and know how to deal with bias i.e. have the ‘mindware’
Mindware
The software of the brain
Processing problems Content problems
Mindwarecontamination
Mindware gaps
Cognitive miserliness
WYSIATIMinimising cognitive effort
Accepting things at face valueInsufficient breadth and depth
Avoiding complexity
Failures of tools of rationalityKnowledge deficits
Impaired scientific thinkingImpaired probability thinking
Being illogical
Knowledge deficitsImpaired scientific thinking
Impaired probability thinkingIgnoring alternate hypothesesSub-optimal critical thinking
Cognitive biasesCultural conditioning
Group cultureIllogical reasoningEgocentric thinking
(Hasty judgments)Hasty Judgments Distorted Probability estimates
Biased Judgments
RationalityFailure
Biased Judgments
190
Dobler et al, BMJEBM 2018
A root cause analysis of thinking
The Behaviour of Biases
Detailed cognitive analysis of 42 cases from EM Biases are common – 232 instances Few instances of knowledge-based errors Usually 5-6 per case Typically appear at certain points in the diagnostic
process
Top 12Rank# # of times Bias
1 17 Anchoring2 16 Diagnosis Momentum3 14 Confirmation Bias4 13 Unpacking Failure5 12 Search Satisficing6 12 Framing7 11 Ascertainment Bias8 11 Psych-Out Error9 10 Fundamental Attribution Error10 10 Triage Cueing11 9 Premature Closure12 9 Omission Error
Breakdown by discipline (42 cases)
• Medicine 18• Neurosurgery 5• Surgery 6• Ophthalmology 3• Orthopedics 3• ObGyn 2• Urology 2• Psychiatry 1
Cognitive autopsy of a medical case
Case A 21 y/o male arrives at the ED with multiple stab wounds to the chest, arms and
head. One of the chest wounds is inferior to the L scapular. OE: Talking, cooperative, inebriated, no dyspnoea or SOB, AE = bilaterally, 02
Sat N; 130/80, HR 80-90. Lac on scapula deep – local wound exploration did not penetrate the pleural cavity, ribs palpable with pleura behind. EDTUS: good views, no free fluid. Serial abdominal exams N, rectal exam N. CXR N.
Lacerations irrigated, explored, and repaired. Discharge Dx: Stab wound chest. D/C Home
5 days later presented to a different hospital with vomiting, blurred vision and difficulty concentrating
CT scan of brain
Cognitive biases
Anchoring: locking onto specific features of a problem and failing to adjust to other aspectsSearch satisficing: after potentially most serious injury is addressed, search is called off for other serious injuries. Posterior probability error: vast majority of scalp wounds previously seen have been benign and WYSIATI.Overconfidence (hubris): Resident is in year 5Cognitive miserliness: ED very busy, fatigue, sleep deprivation, dysphoria
Ambient Dx Risk Situations
• Cognitive overloading• Interruptions/distractions• Sleep deprivation/sleep debt• Negative mood• Fatigue
Main Points
The barometer for failed clinical reasoning is diagnostic failure The current estimate of diagnostic failure is 10-15% The sources of diagnostic failure are the System (25%) and the Individual
(75%) The principle source of individual failure is how the individual thinks and
less what they know The main factor that determines thinking competence is rationality A major cause of rationality failure is vulnerability to cognitive bias Medical education needs to promote rationality
No longer an option…
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