Thinking and errorAnne-Maree KellyDecember 5, 2012
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Diagnostic error Common A top cause of medicolegal actions Up to 20% of autopsies Emergency Medicine is a high risk environment Why?
Diagnostic error “No fault’ error Silent or atypical disease Mimics something more common Lack of patient co-operation or presentation of symptoms Limitation of medical knowledge Systems error Technical: test error, lack of test/resource Organisational: supervision, unavailability of expertise,inefficient processes, cultural issues Cognitive error Faulty data collection or interpretation Flawed reasoning Incomplete knowledge
Cognitive error: My questions Is it predictable? Is it unavoidable?
Your experience Work with the two or three people around you. Can you identify a case that you were involved in orheard about where thinking processes contributed toa diagnostic error?
Cases from the medicolegal world Ms X aged 42 Single mother of 4 Abdominal pain and vomiting Exam difficult due to obesity Three presentations to ED of a tertiary referral hospitalover 5 days Diagnosis #1: gastro (xray and bloods performed) Diagnosis #2: gastro; no further tests Diagnosis #3: bowel obstruction, ARF, gangrenous gut Outcome: death
The issues #1: Assessment was reasonable Xray was performed and clearly showed small bowelobstruction #2: Assessment was brief Assumed that previous diagnosis was correct Did not check results/ xray
The cost 4 children under 15 without a mother (or interestedfather) > 1 million dollars settlement
Case 2 HG aged 3 Rural setting, experienced mum 24 hours of D&V Seen by GP 1: gastro, home for fluids Seen by GP 2 next day: gastro; home for fluids Presented in ED in next town: gastro; home for fluids Day 3 admitted to small rural hospital by GP registrar for oral fluids.Mother concerned re lack of urine. Day 4 evident that there had been no urine output for ~24 hours IV therapy Transferred to large hospital on Day 5 Cardiac arrest, died
The issues First GP assessment fine Second GP assessment Failure of data collection: weight Assumption that all gastro settles with oral fluids Not listening to mum re intake / output ED assessment Failure of data collection: weight Assumption that all gastro settles with oral fluids Not listening to mum re intake / output In hospital management Failure of data collection: weight, fluid balance chart, frequent obs Assumption that all gastro settles with oral fluids Not listening to mum re intake / output ‘It will all be alright’ mentality blocking escalation of care tospecialist centre
Something closer to home 30-something woman Sore throat 24-48 hours Unable to swallow saliva Epiglottis suspected by ED team Difficulty engaging ENT team Eventually came and attempted endoscopic exam Acute hypoxia Surgical airway Alive...but close run thing
Issues Epiglottis now very uncommon Dismissed the likelihood despite reasonable evidence Failure to respect assessment of clinician actuallyseeing the patient
Types of cognitive predispositions to respondType of CDR ExplanationAggregate bias Failure to believe aggregate data, eg guidelines‘My patient is different’Anchoring Locking on to features in presentation too early andfailing to adjust with further dataAscertainment bias Thinking shaped by prior expectation eg genderbias, stereotypingAvailability Diagnosis is more likely if it readily comes to mindBase-rate neglect Tendency to ignore the true prevalence of adisease, impacts Bayesian thinkingCommission bias Belief that harm can only be prevented by action;tendency to action rather than inactionConfirmation bias The tendency to look for confirming evidence ratherthan evidence to refuteDiagnosis momentum Diagnoses are like sticky labels; once attached hardto remove
Types of cognitive predispositions to respondType of CDR ExplanationFeedback sanction Error not temporarily associated with immediateconsequencesFraming effect The way we see things is influenced by how they arepresented to us (gastro and positive stool for bloodstory)Fundamental attribution error Blame patients for illness rather than look at situationalfactorsGambler’s fallacy Pretest probability of a particular diagnosis influencedby previous but independent events (eg coin tossexample)Gender bias False belief of difference in probability of a diagnosisbetween gendersHindsight bias Knowing what happened influences the perception ofpast events and inhibits realistic appraisal of why erroroccurred
Types of cognitive predispositions to respondType of CDR ExplanationMultiple alternatives bias Multiple options cause uncertainty; tendency to limitoptions to those we know and potentially ignore rareralternativesOmission bias Tendency towards inaction, usually for fear of doingharmOrder effects Information transfer is U shaped; we ‘hear’ better at thebeginning and end. May miss important stuff in themiddleOutcome bias The tendency to opt for diagnoses with good outcomesOver-confidence bias Belief that we know more than we do!Playing the odds In ambiguous situations, a tendency to opt for the lessserious diagnosisPosterior probability error The tendency to be unduly influenced by what hasgone on before (see case 1)
Types of cognitive predispositions to respondType of CDR ExplanationPremature closure Very powerful: Tendency to accept a diagnosis before itis fully verifiedPsych-out error Tendency for error in psych patients especially missingof serious medical issuesRepresentativeness restraint Looks like a duck, quacks like a duck, is a duckMissing atypical presentationsSearch satisfying Inappropriately calling off the search once somethinghas been foundSunk costs The more we ‘invest’ in a diagnosis, the less likely weare to relese itSutton’s slip Going for the obviousTriage cueing Triage assignment falsely prompts bias towardsserious/ non-serious illnessUnpacking principle Failure to elicit all relevant information
Types of cognitive predispositions to respondType of CDR ExplanationVertical line failure Thinking in silos; inflexible thinking; failure to considerwhat else might this be?Visceral bias Visceral arousal is associated with poor decisionsFeelings towards patients (positive and negative) mayresult in diagnoses being missedOur pre-disposition to CDR depends on:•Personality•Experience•Self-awareness•Environment/ situation
Avoiding cognitive error: Exercise Group 1: In pairs or threes,describe strategies thatmight help cliniciansavoid CDR in patientsthey manage Group 2: In pairs or threes,describe strategies thatmight help supervisingclinicians/ consultantsavoid CDR in casesthey are consultedabout
Cognitive de-biasing strategiesStrategy Mechanism/ ActionDevelop insight/ awareness Talking about and analysing diagnostic errorsSharing experienceConsider alternatives Establish processes that ‘force’ consideration ofother diagnosesRoutinely asking What else might this be?Documenting why you consider something unlikelyand whyDevelop reflective approach toproblem solvingRegularly ask yourself how you are thinking aboutdiagnostic problems and how you might do it betterDecrease reliance on memory System level: cognitive aids, guidelines, etcPersonal level: Don’t rely on memory. Look thingsup!Specific training In CDRIn probability theory and Bayesian thinkingSimulation Both as case discussion and in simulator training
Cognitive de-biasing strategiesStrategy Mechanism/ ActionCognitive forcing strategies Develop specific strategies for particular high risksituations eg medical clearance of psychiatricpatientsMake it easier More information readily availableMinimise time pressures More time to think usually means better decisionsAccountability Clear accountability and followup of decisionsmadeFeedback Rapid and reliable feedback esp. re diagnostic erroror ‘good picks’ assists diagnostic ‘calibration’Teamwork Two heads are better than one. Informationsharing/consultation with other team members egnurses, other doctors, allied health etc.
Summary Diagnostic error and how we think are intimatedassociated Cognitive errors can be reduced by: System measures to promote information availability and‘force’ consideration of high risk groups/ diagnoses Personal measures such as self-awareness, de-biasingstrategies Training Teamwork