Inside Medicine: 15 percent of the time, doctors’ diagnoses are off the mark

Published: Wednesday, Feb. 12, 2014 - 4:00 pm

Lindsay came to the emergency room with a bad cough and shortness of breath. She also told the doctors she had a bad headache and nausea, and had a history of anxiety issues for which she took some medication. Four hours later, after X-rays and blood tests results came back, the doctors diagnosed bronchitis with anxiety and sent Lindsay home with a prescription for antibiotics. They advised her to follow up with her primary care doctor (she had none).

Doctors were wrong about her bronchitis. In this case, the problem wasn’t a bad or ignorant doctor – it was a problem in thinking, only selectively listening to the patient, and in too quickly jumping to conclusion before considering other possibilities.

Doctors’ diagnoses are wrong at least 15 percent of the time. It turns out that doctors who make the fewest diagnostic errors are those whose work involves seeing something specific like a rash (dermatologists) or an abnormal X-ray (a radiologist). Doctors who see lots of patients coming in with very different diagnoses (such as pediatricians, emergency physicians and family physicians) are the most likely to make mistakes. They have a huge number of conditions to consider and their attention can be easily diverted to one symptom while overlooking other clues that might lead to a different diagnosis.

Cognitive psychologists study how doctors think and why they make errors, and they have identified common patterns. Not surprisingly, the thinking errors that doctors make are common to human nature. For example, things that happen often are often given more emphasis than things that happen rarely. As an example, when you think about what to make for dinner tonight, the options you consider first, and the choice you will likely settle on for dinner, is probably something you’ve made recently, not a rare dish you made once several years ago or read about. The same logic is true with doctors. What comes to mind first are common diagnoses they see often, not a rare disease that they saw once eight years ago.

Cognitive psychologists describe two common types of thinking. The first, called intuitive thinking, drives automatic behaviors – thing we do regularly without even thinking about them, such as brushing our teeth before bedtime. These patterns of behaviors are developed through repeated experiences that make them automatic.

In medicine, when doctors trust their intuitive thinking, they will be right more often than not, but such thinking can lead to huge mistakes when things don’t fit the usual pattern. This was the case for Lindsay, who was diagnosed with bronchitis because the doctor focused on her respiratory symptoms and ignored her mentioning a bad headache. In contrast, the second type of thinking called analytic thinking is deliberate and requires mental effort and time but more often leads to the right diagnosis. However, if human beings invested mental energy and time for every decision, very little would ever get done.

There are many biases that also affect doctors’ thinking. People with mental illness or those with certain physical or behavior traits are often assumed by doctors to have a certain set of problems. This is not irrational, because they often due share some patterns of medical illness, but trouble comes in assuming that typical because on occasion all types of people get unusual diseases. Health care providers need to become aware of their biases so that when someone comes in that might trigger a bias they can consciously move to an analytic mode of thinking.


Michael Wilkes, M.D., is a professor of medicine at the University of California, Davis. Identifying characteristics of patients mentioned in his column are changed to protect their confidentiality. Reach him at drwilkes@sacbee.com.



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