Read on Twitter
1/ Clinical Reasoning Series – Cognitive Bias
Ever felt the thrill of making crucial diagnosis? The pain of missing a diagnosis? Yeah, us too
Clinical reasoning is hard, so let’s talk about it. Our 1st post in a new series starts today. Let’s talk about Biases.
#MedTwitter
Ever felt the thrill of making crucial diagnosis? The pain of missing a diagnosis? Yeah, us too
Clinical reasoning is hard, so let’s talk about it. Our 1st post in a new series starts today. Let’s talk about Biases.
#MedTwitter
2/ Basic Definitions:
>Heuristic: a cognitive shortcut based on prior experience & pattern recognition
>Cognitive Bias: when a heuristic leads to misdiagnosis or inappropriate treatment
We need heuristics b/c reasoning every decision from 1st principles would take forever!
>Heuristic: a cognitive shortcut based on prior experience & pattern recognition
>Cognitive Bias: when a heuristic leads to misdiagnosis or inappropriate treatment
We need heuristics b/c reasoning every decision from 1st principles would take forever!
3/ Heuristic vs Bias
There is a fine line b/t a heuristic and a bias
For example: 80yoM w/ CAD p/w SOB, ankle edema, and alveolar filling on CXR. You start abx PNA
If he improves, PNA was a good call
If he gets worse because he has 
failure, PNA was “premature closure”
There is a fine line b/t a heuristic and a bias
For example: 80yoM w/ CAD p/w SOB, ankle edema, and alveolar filling on CXR. You start abx PNA
If he improves, PNA was a good call If he gets worse because he has failure, PNA was “premature closure”
4/ Cognitive Biases
Heuristics are based on knowledge and prior experience. The more you practice and learn, the better you become at using them. Biases happen when heuristics go wrong.
Check out this comparative list of heuristics and biases.
Chart by @CaseyMcQuadeMD
Heuristics are based on knowledge and prior experience. The more you practice and learn, the better you become at using them. Biases happen when heuristics go wrong.
Check out this comparative list of heuristics and biases.
Chart by @CaseyMcQuadeMD
5/ Errors of Prevalence and Errors of Ego
Most biases fit into 1 of these 2 categorie:
You forgot the base rate of a disease - base rate neglect, representativeness restraint, availability bias
You want to be right (and don't we all?) - confirmation bias, premature closure
Most biases fit into 1 of these 2 categorie:
You forgot the base rate of a disease - base rate neglect, representativeness restraint, availability bias You want to be right (and don't we all?) - confirmation bias, premature closure
4/ Check for Understanding (give this case a try!)
40yoF w/ obesity p/w RUQ pain, anorexia
VS normal
RUQ pain. Murphy’s sign negative. No icterus
WBC 14, AST 300, ALT 400, HAV/HBV/HCV neg
RUQ US: dilated CBD, no stones
>ANA = 1:320
Q1: Which diagnosis is most likely?
40yoF w/ obesity p/w RUQ pain, anorexia
VS normalRUQ pain. Murphy’s sign negative. No icterusWBC 14, AST 300, ALT 400, HAV/HBV/HCV negRUQ US: dilated CBD, no stones>ANA = 1:320
Q1: Which diagnosis is most likely?
5/ Answer #1
A passed gallstone is most likely based on the prevalence of gallstones, CBD dilation, & elevated LFTs (commonly caused by gallstones/cholangitis)
Your MS3 saw autoimmune hepatitis last month and thinks AIH is most likely here.
Q2: What biases are likely at work?
A passed gallstone is most likely based on the prevalence of gallstones, CBD dilation, & elevated LFTs (commonly caused by gallstones/cholangitis)
Your MS3 saw autoimmune hepatitis last month and thinks AIH is most likely here.
Q2: What biases are likely at work?
6/ Answer #2
All are possibly correct (I can’t read your student’s mind...):
Gallstones are common, AIH is rare
They just saw AIH recently (availability)
They focus on the ANA (nonspecific) but disregard the dilated CBD
“No gallstones” is not “classic” of gallstone dz
All are possibly correct (I can’t read your student’s mind...):
Gallstones are common, AIH is rareThey just saw AIH recently (availability)They focus on the ANA (nonspecific) but disregard the dilated CBD“No gallstones” is not “classic” of gallstone dz
7/ Next Steps
So how do you combat bias?
Turns out it’s very hard:
Things that may decrease bias:
-Doing an ”effortful pause” to check yourself for bias
-Using diagnostic frameworks (e.g @CPSolvers)
-Using
lists
Remembering to do these is hard even with practice!
So how do you combat bias?
Turns out it’s very hard:Things that may decrease bias:
-Doing an ”effortful pause” to check yourself for bias
-Using diagnostic frameworks (e.g @CPSolvers)
-Using
lists Remembering to do these is hard even with practice!
8/ Further Reading
Thanks for reading!
We’re going to keep this series going in the future. If you’re interested in reading more, check out these:
“Thinking, Fast and Slow” by Daniel Kahneman
“Sources of Power” by Gary Klein
https://pubmed.ncbi.nlm.nih.gov/32311734/
https://qualitysafety.bmj.com/content/26/2/87
Thanks for reading!
We’re going to keep this series going in the future. If you’re interested in reading more, check out these:
“Thinking, Fast and Slow” by Daniel Kahneman
“Sources of Power” by Gary Klein
https://pubmed.ncbi.nlm.nih.gov/32311734/
https://qualitysafety.bmj.com/content/26/2/87
