Physicians are often required to interpret medical literature to make critical decisions on patient care. Given that it is often in a hectic and hurried environment a strong foundation of evidence-based medicine is paramount. Unfortunately, this study from JAMA showed that physicians at all levels of training have anything but that.
This group surveyed a mix of medical students, interns, residents, fellows, attending physicians and one retired physician. They were asked to answer the following question:
“If a test to detect a disease whose prevalence is 1/1000 has a false positive rate of 5%, what is the chance that a person found to have a positive result actually has the disease, assuming you know nothing about the person’s symptoms or signs?”
Unfortunately three-quarters of the subjects got the answer wrong. The results were consistent across all levels of training. The most commonly given answer was almost as far from correct as possible.
I’ve withheld the answer for those who want to try out the questions themselves, and I know all the dedicated EMLoN readers will fare much better.
“Medicine’s Uncomfortable Relationship With Math: Calculating Positive Predictive Value”
http://archinte.jamanetwork.com/article.aspx?articleid=1861033
[I gave this same test to our residency program – and the results were almost identical. A few sample “answers” below. -Ryan]