PATIENT INTERPRETATIONS OF TERMS CONNOTING LOW PROBABILITIES WHEN COMMUNICATING ABOUT SURGICAL RISK

The objectives of this study were to assess the meaning ascribed by pa tients to verbal expressions commonly used in medical care (informed c onsent prior to a surgical procedure) to describe events that have a l ow probability of occurring. The study consisted in a cross-sectional survey of 116 consecutive patients seen in a general medicine clinic, i.e., a university-based Department of Veterans Affairs Medical Center . Subjects were given a randomly ordered list of 17 terms commonly use d in informed consent sessions prior to surgery, each a qualitative ex pression of low probability. They were asked to indicate what they und erstood to be the numerical meaning of each word. Fifty-two percent of patients used percentages between 0 and 1 for at least one of the ver bal probability terms. Ten of the 17 terms were assigned probabilities of less than 1%. For these ten probability terms, 13% of patients ass igned a probability of > 50% to at least one term. These results confi rm that there is great variation among patients in how they interpret low-probability terms in the medical context. In addition, this study suggests that routine use of verbal probability scales may help physic ians to better understand which patients need more help in understandi ng medical risk in their own decision making.