But I’m not biased
When we hear the word “bias” it conjures up images of evil and ignorant people who let rumor and stereotypes fuel their judgement. While it is true that doctors sometimes have unspoken, visceral, automatic reactions to some patients (as in “That patient is drug seeking and not really in pain.”) there are also more innocent biases that interfere with our thinking. At the same time, there are patients who meet a doctor and assume that they will be mistreated also based on a visceral reaction (as in “That doctor won’t understand my social position and will blame me if the prescription doesn’t work even if it’s because I can’t afford it so I only take half to make it last longer.”)
The kind of bias that interferes with our clinical reasoning can be described in the ways below:
Premature Closure
Includes Anchoring, Representativeness restraint, Confirmation bias
Once you get an idea that you think is correct it is hard for many of us to let go of that idea. Sometimes that means that data that confirms your diagnosis is accepted and data that contradicts it is ignored. You might hear “Patients don’t read the book” or “This is a variant of that syndrome” as excuses to ignore contradictory data.
Prejudice
Includes Psych out, Gender, Visceral
We have all seen patients whose appearance influences our thinking. We have all seen patients who we like so much that terrible diagnoses and painful tests are not considered. We have all seen patients with psychiatric illnesses in whom real somatic diagnoses are not considered (Psych Out Bias).
Insufficient Knowledge
Includes Availability, Ascertainment
They say that to a hammer, everything looks like a nail. If all you’ve got available to you is heart failure then every patient with shortness of breath might have a “component of heart failure” and your go to treatment will include diuretics. Stopping and looking things up should never be seen as a weakness.
Fatigue
Includes Order effect, Zebra retreat, Multiple alternative
Have you ever stopped for directions and the person you asked says “Oh yes, you make a right and go two miles then turn left at the bowling alley and left again at the “Stop and Shop” but NOT at the Whole Foods then get on highway 42 and go another 5 miles”
But all you hear is “Make a right and Highway 42 and then something else”
That’s an example of order effect. It happens especially when you are fatigued.
Zebra Retreat is when a potential diagnosis is so rare and complicated that no one wants to take the time to research it so they just back off.
Gambling
Includes Sutton’s slip, Posterior probability
There is an apocryphal story that when they captured Willy Sutton the bank robber they asked him “Hey Willy, why do you rob banks?” and Sutton responded “That’s where the money is.” There are only two problems with this story. a) it never happened and b) it’s not always true.
Gambling as a bias has to do with going with a hunch or simply choosing an outcome and hoping for it.