Communicating risk with words: One person's 'rare' is another person's 'common'

Clinical Question

How do patients interpret word-based and number-based probability estimates, and how do they prefer to receive estimates of risk?

Bottom line

In general, people grossly overestimate probabilities conveyed by the words we use. People translate "rare" as 10%, on average, which is 100-fold higher than its intended meaning when used for medication risk labeling. The interpretation of "common" — an average 59% — is much closer, in my mind, to "almost always" than the accepted definition of 1% to 10%. Patients may prefer hearing the actual numbers, if you can provide them. I suspect, though, that numbers will be misinterpreted given the general state of innumeracy in most of us (imagine, perhaps, your own difference in interpretation if I had written "100-fold" instead of "2 orders of magnitude" in the synopsis). 1a-

Study design: Systematic review

Funding: Government

Setting: Other


Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Tufts University
Boston, MA

Discuss this POEM



Communication with patient and family

Different perceive different meaning from what you say
you have engage patient in dialogue and explain clearly and extensively and answer questions, It takes time but it is important.

Robert Wallace Shepherd

Communicating risk with words

The comment about "orders of magnitude" is apt. Doctors and especially scientists use "orders of magnitude" to prove that they are part of the club, but the term is virtual bafflegab. Try the following substitute: two orders of magnitude is a hundredfold, while three orders of magnitude is a thousandfold.
Another peeve is the current use of "profound" to mean "really big." Anyone with knowledge of a language derived from Latin knows that profound means deep or low. "Profoundly big" is a contradiction.


patients interpretation of risk words

for example, rare means 10% to some people but actually not any where close