Formats for improving risk communication in medical tradeoff decisions.

To make treatment decisions, patients should consider not only a treatment option's potential consequences but also the probability of those consequences. Many laypeople, however, have difficulty using probability information. This Internet-based study (2,601 participants) examined a hypothetical medical tradeoff situation in which a treatment would decrease one risk but increase another. Accuracy was assessed in terms of the ability to determine correctly whether the treatment would increase or decrease the total risk. For these tradeoff problems, accuracy was greater when the following occurred: (1) the amount of cognitive effort required to evaluate the tradeoff was reduced; (2) probability information was presented as a graphical display rather than as text only; and (3) information was presented as percentages rather than as frequencies (n in 100). These findings provide suggestions of ways to present risk probabilities that may help patients understand their treatment options.