1. Chris Feddock, MD, MS Andrew Hoellein, MD, MS
Clinical Reasoning
Chris Feddock, MD, MS
Andrew Hoellein, MD, MS

2. Learning Objectives
Describe the cognitive processes of expert diagnosticians
Recognize the shortcomings of various diagnostic strategies
Foster the development of clinical reasoning in bedside teaching

3. Systems System 1 Intuitive & Heuristic System 2 Analytic & Systematic
Fast
Slow
Little conscious control
High cognitive awareness
Low reliability
High reliability
Errors are relatively common
Rare errors (but significant ones)
High emotional attachment
Low emotional attachment
Low scientific rigor
High scientific rigor
Am J Med. 2008;121: S24–S29.

4. Intuitive System

5. Pattern Recognition Representativeness Heuristic
Recognition of the prototypical pattern of disease
“If it looks like a duck, walks like a duck, quacks like a duck, then it is a duck.”
Med Educ. 2004;39:

6. Shortfalls of Inductive Reasoning

7. Poggendorff Illusion, 1860.

8. Previously Encountered
16 clinical cases reviewed and discussed
4 cases similar to those encountered previously
Provide a diagnosis
4 cases distinct from those encountered previously
First and Second Year Internal Medicine Residents
0 = incorrect diagnosis
0.5 = partially correct
1 = fully correct
Which residents had greater diagnostic accuracy?
Does it matter if they have seen the case previously?
Previously Encountered
Novel
First Year Residents
2.03 ( )
1.42 ( )
Second Year Residents
1.55 ( )
2.19 ( )

9. Analytical System

10. Hypothetico-Deductive Process
Accept Hypothesis
Data Collection
New Hypothesis
Prediction
Adequacy
Coherency
Parsimony
Reject Hypothesis
Med Educ. 2004;39:

11. Shortfalls of Analytical Reasoning

12. The “Door” Study http://www.youtube.com/watch?v=FWSxSQsspiQ
Psychonomic Bulletin & Review ;5:644-9.

13. What diagnostic strategy is best?

14. First and Second Year Internal Medicine Residents
16 clinical cases reviewed and discussed
4 cases similar to those encountered previously
Quick diagnosis
Analytic Diagnosis
Read the case
Write down the diagnosis previously given for the case
List the findings in the case description that support this diagnosis
List the findings that speak against this diagnosis
List the findings that would be expected to be present if the diagnosis were true but were not described in the case
Nonanalytical
Analytical
First Year Residents
2.03 ( )
2.31 ( )
Second Year Residents
1.55 ( )
2.03 ( )

15. No single diagnostic strategy
Diagnostic error occurs with both strategies
Heuristic error
Cognitive overload – can only process small amounts
Experts move between analytical and intuitive
Efficient tailoring of key information
Synthesize data to reach a diagnosis (forward reasoning)
Knowledge organized into schemes

16. Teach Clinical Reasoning
Make learner’s commit to a diagnosis or a narrow differential
Must be actively engaged in decision-making
Emphasize pattern recognition
Teach context specificity
Continual development of more sophisticated illness scripts
Think about your thinking (out loud!)
Self-reflect on diagnostic decision-making
Admit to clinical reasoning failures

17. Learner #1 “I think it is most likely GERD vs. anxiety.”
65 year-old woman
Lost mother recently
“chest burning” began today
Radiates to right arm
Nausea/vomiting
Did not respond to anti-acids
History of diabetes
“I think it is most likely GERD vs. anxiety.”

18. Learner #1 – insufficient knowledge
Metacognition – dual process thinking
Problem representation
Illness scripts
Likelihood ratios

19. Learner #1
65 year-old woman with diabetes (45% chance of MI) and chest discomfort
2 hours of “chest burning” (LR = 1.3)
Radiates to right arm (LR = 7.3)
Nausea/vomiting (LR = 3.5)

20. Learner #2
54 year-old woman
“Boring” abdominal pain for 1 day
Nausea
Drinks 3-4 beers/night
Non-smoker
Abdomen with voluntary guarding
“I think it is a AAA because my uncle had one and he presented like this.”

21. Learner #2 - biased Look for bias/heuristics - shortcuts
What else could this be?
Why would a non-smoking 54 y/o woman have a AAA?

22. Bias-prone Heuristics
Definition
Anchoring
Focus on features too early without adjusting with more data
Emotional
Feelings influence diagnosis (non-adherent patient)
Availability
Recently encountered
Confirmation
Look for confirming evidence only
Blind obedience
Undue deference to authority/technology
Framing
Source of info and how it is framed
Unpacking
Failure to elicit all pertinent info
Diagnostic momentum
Failure to consider diagnostic eval due to prior diagnostic label
Academic Internal Medicine Insight

23. Learner #2 Pancreatitis Cholecystitis Appendicitis AAA
Older women < 2%
Smoking
Family history
Absence of mass/bruit (LR- .43)

24. Learner #3 “This must be COPD because he is a smoker.” 40 y/o man
Progressive shortness of air for 3 days
20 pack year smoking history
Non-productive cough
Modest dyspnea on exertion
Temp 100.5
“This must be COPD because he is a smoker.”

25. Learner #3 - overconfident
State confidence about diagnosis
Describe biases
What else could this be?
Do all smokers develop COPD?

26. Learner #3 Anchoring bias Availability bias Confirmation bias
Smoking < 30 years + no wheezing symptoms + no wheezes on exam
-posterior odds of obstructive airways = 0.02%

27. Learner 4
18 year-old woman hurt left knee playing lacrosse
“popping” sensation when planted left foot
Difficulty bearing weight
Small effusion present
Lachman positive
McMurray indeterminate
“This could be a ACL tear but still could be a meniscal injury or maybe even torn patellar tendon…
I don’t know!”

28. Learner #4 - underconfident
Diagnostic “time out”
Review history and physical

29. Learner #4 Classic injury pattern for ACL Women RR > 2
Lachman LR+ 42

30. Thank you Chris Feddock Andrew Hoellein cafedd00@uky.edu