PATIENTS INTERPRETATIONS OF VERBAL EXPRESSIONS OF PROBABILITY - IMPLICATIONS FOR SECURING INFORMED CONSENT TO MEDICAL INTERVENTIONS

Physicians often use verbal expressions of probability to characterize their uncertainty about outcomes and the risks or side effects of pro posed therapies. However, there is an extensive literature that docume nts the inherent vagueness of such expressions. Because of the potenti al importance of probability terms to physician-patient communication and decision-making, we asked patients to tell us the odds they though t applicable to the term ''rare,'' as used by their physician to discu ss the likelihood of an adverse outcome from surgery. Patients were ra ndomly assigned to one of three outcome groups: death, severe heart at tack, or severe pneumonia. Demographic data were elicited from each su bject, as were indicators of present health status, medical history fo r certain diseases and surgery, and life expectancy. Linear regression and ANOVA analyses of the responses indicate that patient age, educat ion level, perceived health status, recency of experience with disease and medical care influence patients' numeric interpretations. We disc uss the implications of these results.