Earlier this week, I saw a segment on the Nightly News claiming 1 in 20 people have a misdiagnosis – based on a new study that had come out that day.  That error rate translates into 12 million Americans per year.  As a physician I find that number startling.  As a physician who specializes in making the proper diagnosis, and who advocates that you can’t be well without a proper diagnosis, I wanted to delve deeper into this report.  If accurate, I am making 1 or 2 mistakes a day!

What was the study about?

So how did they make the claim that 1 in 20 patients have a misdiagnosis?  How was a misdiagnosis defined?

The study looked at 3 earlier studies and combined the results.  One was a study in a primary care setting that defined a potential error as an unscheduled hospitalization or return visit within 14 days of the initial appointment.  Then they looked at the records of those cases to decide if a misdiagnosis occurred – defined as the information to make a correct diagnosis existed at the time of the first visit.

The other 2 studies looked at delay of diagnosis for colon cancer and lung cancer.  They defined a misdiagnosis as lack of follow-up of a “red flag” – an abnormality or symptom that should trigger further evaluation.

What did they find?

In the primary care study, they found 177 errors in 1343 records.  In the colon cancer study, they found 26 errors in 291,773 records.  Finally, in the lung cancer study, they found 127 errors in 587 records.  These results were combined and applied to the US population to come up with the number of 1 in 20 mistakes or 5% of the US population having a misdiagnosis – based on 330 errors found in 293,703 actual reviews.

What does this mean?

No profession is perfect – we are all human – so errors are a matter of consequence – if I was a baseball player who had a .950 batting average, I’d be playing for the Yankees.  Errors happen in medicine, just as in any profession.   It is less critical if you are told you have allergies when you have a cold – both are treated similarly and not life threatening.  However, being told your chest pain is heartburn when you are having a heart attack can have serious consequences.

A misdiagnosis is a serious issue.  Trying to define the rate and circumstances where a misdiagnosis occurs should be studied more, and ways of improving the practice of medicine explored.  I do feel the statistical manipulations in this study and generalizing their results to the entire US population oversimplified this issue.

I reviewed the thought process of a physician in an earlier post.  It involves re-evaluating a person’s symptoms as more information comes in.  Being willing to reconsider a diagnosis is key to being a good doctor – and avoiding a misdiagnosis.

I hope this review of a headline helps put it in perspective.  I plan to do this regularly – a second opinion of health news.  So, if you see or read a story you’d like to learn more about, let me know – I’ll give you A Second Opinion.

The path to wellness begins with a proper diagnosis

Published by Eric Goldberg, MD, FACP

I am a Board Certified Internal Medicine physician. I currently practice at and am the Medical Director of NYU Langone Internal Medicine Associates. Posts are my opinion and not medical advice or an official position of NYU Langone Medical Center.

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