Individual Errors and Heuristics

1. Individual Errors and Heuristics Ethan Cumbler M.D. Assistant Professor of Medicine Hospitalist Section University of Colorado Hospital 2007 THE UNSINKABLE TITANIC

2. The Psychology of Medical Error • In the first module we discussed systems issues in relation to medical error. • In this module we will discuss individual errors.

3. Medical Cognition • Hypothesis generation (data to hypothesis) • Followed by • Hypothesis evaluation

4. Deductive reasoning • Drawing conclusions based on a set of assumptions • All lizards are reptiles • No cats are reptiles • Therefore no cats are lizards • Deductive reasoning breaks down when the truth of a premise is unclear or when a premise is false.

5. Inductive reasoning • Takes us from the observed to the unobserved. • Since the sun has risen every day we induce that it will likely rise again tomorrow. • Leads to the black swan fallacy of inductive reasoning. Just because every swan we have ever seen is white does not mean that there can not be a black swan.

6. Abductive reasoning • Combines deducuctive and inductive reasoning in medical thinking • Uses deductive thinking to generate hypotheses then inductive reasoning to test and potentially rule out each one. • Iterative Hypothesis Testing

7. These descriptions of decision making likely do not reflect the real world of medical cognition which involves both explicit conscious decision making but also “fuzzy logic” in a highly complex milieu • Perhaps this is why the hospital is described as a “natural laboratory of error”

8. Types of Errors • Knowledge- mistake from inadequate or incomplete information. Least common • Rule based- the incorrect application of the information ie patient with chest pain due to MI thought to be costochondritis. We think of this as a “lapse of judgement” • Skill based- performance error ie intended to correct potassium but forgot. Most common. We think of this as a “slip”

9. Types of Errors • Rule-based judgment errors may seem like unpredictable events but cognitive dispositions referred to as heuristics lead to predisposition to judgment error under predictable circumstances.

10. Hueristic • Involving or serving as an aid to learning, discovery, or problem-solving by exploratory techniques that use self education • Comes from the Greek term heuriskein for discovery • In medical decision making we frequently think of these as mental shortcuts which allow physicians to move forward with the thousands of decisions which are needed each day without painful baysean analysis for each one.

11. Heuristic failures • Goal of the physician is to recognize that while heuristics are useful, they also can set you up for errors • Sometimes this is referred to as “Cognitive dispositions to respond” • Understanding how the mental shortcuts we take can lead to predictable mistakes takes some of the apparent randomness out of medical error

12. Heuristic Failures • Think of this as the use of “cognitive forcing strategies” to avoid error • Similar concept when we recommend a CT scan prior to LP for a patient who is obtunded and febrile. Recognizing the potential for inadequate neurologic exam for focality we routinely perform the scan. Think how different this is then simply recommending the physician “try harder to get a good exam”

13. Selected CDRs • Anchoring: • The tendency to lock on to the features of the early presentation and not adjust the initial impression in light of later information • This can be further exacerbated by the confirmation bias and the sunk cost bias • Confirmation Bias: • The tendency to seek confirming evidence to support a diagnosis rather than look for elements which would refute the hypothesis • “Sunk Cost Bias” in which the clinician becomes unwilling to abandon a diagnosis into which considerable effort has been expended

14. Selected CDRs • Availability Bias: • Disposition to judge a diagnosis as being more likely if you have seen it more recently. • Are there more words which start with the letter R or which have the letter R in the 3rd position? • Which kills more people. Homicide or gastric cancer?

15. Selected CDRs • Commission Bias: • Tendency to prefer action to inaction • Omission Bias: • Tendency towards inaction “first do no harm” • Typically Omission is more common than Commission. The most common cause of malpractice in the ER is failure to diagnose

16. Selected CDRs • Diagnosis Momentum: • The tendency for a diagnosis to become “stickier” with repetition. • Think of this as a potential pitfall of the electronic medical record where an incorrect allergy can be repeated in subsequent notes gaining veracity with each note which sites it.

17. Selected CDRs • Framing Effect: How the diagnostician sees things is influenced by the way it is presented • “patients with dementia who require CPR have a 95% chance of dying prior to discharge” versus “patients with dementia who require CPR have a 5% chance of surviving to discharge”

18. Selected CDRs • Fundamental Attribution Error: • The tendency to give greater weight to the patients characteristics then to other elements of the situation • Think about a patient with schizophrenia who is agitated and it is attributed to psychosis rather than a foley with bulb inflated in the urethra

19. Selected CDRs • Gambler’s Fallacy: • The incorrect belief that the next item in a sequence of events will be influenced by the results of the preceding events even though they are independent. • If 10 flips of the coin turn up heads then surely the next one will be tails…… right?

20. Selected CDRs • Multiple Alternatives Bias: • The tendency when faced with multiple potential possibilities to try to simplify it to a less complex list by ignoring some options. • Also the tendency to be paralyzed by multiplicity of options.

21. Selected CDRs • Order Effects: • The tendency to pay more attention to the first part of a set of information (primacy effect) or the last part (recency effect) • Leads to error if the middle bit is just as important

22. Selected CDRs • Triage Cueing: • The initial selection of location or specialist has disproportionate influence on subsequent care. • “geography is destiny”

23. Selected CDRs • Premature Closure: • The tendency to accept a decision before it is completely verified • “When the diagnosis is made….the thinking stops” • Satisfied Search, the bane of the radiologist, is a variant of this CDR

24. Other CDRs • Base-rate neglect: incorrect assessment of the prevalence of a disease • Feedback sanction: a system issue where errors can be repeated if the error has no immediate consequence • Gender bias: Form of Ascertainment Bias • Hindsight bias: Knowledge of outcome influences perception of past events • Outcome bias: A form of Value Bias where the physician favors the diagnosis they hope for rather than what is most likely

25. Other CDRs • Overconfidence Bias: A universal tendency to believe we know more than we do • Unpacking principal: the more specific a description of an illness, the more likely it is judged to exist • Vertical line failure: overly limited “silo thinking” • Visceral bias: emotional arousal leads to poor decision making • The Aggregate Fallacy: The belief that the individual patient is atypical from that of aggregate data (such as those used to develop clinical practice guidelines)

26. Other CDRs • Representativeness Restraint:The diagnostician looks for typical presentations. “looks like a duck, quacks like a duck, probably a duck”. Will lead you to miss an atypical presentation. Sometimes called “Suttons Slip” after the bank robber who famously said he robs banks because “that’s where the money is” • Ascertainment Bias: When prior expectations shape thinking. Example would be a racial or gender stereotype

27. Cognitive De-biasing strategies • Awareness of types of CDRs • Forced consideration of alternative possibilities such as differential diagnosis on initial presentation and with interval reevaluations. • Metacognition which refers to a reflective consideration of the logical process • Minimize time pressure • Feedback • Simulations • Cognitive aids (such as algorithms)

28. Putting Theory Into Practice • Begin Case Study in Heuristics Error

29. References • Croskerry P. The Importance of Cognitive Errors in Diagnosis and Stratagies to Minimize Them. Acad Med 2003;78:775-780 • Graber M, Gordon R, Franklin N. Reducing Diagnostic Errors in Medicine: Whats the Goal? Acad Med 2002;77:981-992 • Redelmeier DA, Ferris LE, Tu JV, Hux JE, Schull MJ. Problems For Clinical Judgement: Introducing Cognitive Psychology as One More Basic Science. JAMC 2001;164:358-360 • Human Error. Reason, James. Cambridge University Press, Cambridge 1990. • How Doctors Think. Groopman, Jerome. Houghton Mifflin Company, New York 2007.

30. References • Redelmeler DA. The Cognitive Psychology of Missed Diagnoses. Ann Intern Med 2005;142:115-120