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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-
Reference
Study design: Systematic review
Funding: Government
Setting: Other
Synopsis
These researchers followed PRISMA guidelines to search several databases to find English-language experimental and quasi-experimental studies that evaluated different formats (numerical vs word-based) for presenting health-related quantitative information to patients. Two researchers selected the studies, and 3 researchers abstracted the studies. The review included 33 studies that evaluated the way probabilities were presented and the resultant interpretation. There is a lot to unpack in this report, but here are the main points. One person's "rare" occurrence is another person's "common" occurrence. "Rare," defined by the European Commission (EC) labeling guidelines as between 0.1% and 0.01%, was defined as 2 orders of magnitude higher by study patients (average 10%; range 7% - 21%). "Common," defined by the EC as a risk of 1% to 10%, was thought to mean an average of 59% (range 34% - 70.5%) by patients. In studies asking for preference, a majority of patients prefer numbers rather than word-based estimates of risk.
Reviewer
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Tufts University
Boston, MA
Comments
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.
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