Patients' and Physicians' Interpretations of Graphic Data Displays

Abstract

To assess how patients' and physicians' treatment preferences are influenced by graphic data displays (five-year survival curves), a cross-sectional survey of patients, physicians, and medical students was done in a university-based Department of Veterans Affairs Medical Center. Participants in the study were 119 patients seen in a general medicine clinic, 43 physicians, and 67 medical students. Three five-year survival graphs were used. Each graph contained survival curves for two alternative unidentified treatments for an unidentified med ical condition. Graph 1 was a baseline graph used in previous studies of framing effects. Graph 2 contained one survival curve having an area under the curve that was 24% greater than that in graph 1. Graph 3 contained one survival curve that had an area under the curve that was 42% greater than that in graph 1. Respondents were asked to indicate which treatment they preferred for each graph and which aspects of the five-year survival curves most influenced their choices. Respondents did not receive numerical data about the dif ference between the areas under the two curves. Most patients did not change their pref erences across the three graphs. A significantly larger (p ≤ 0.0001) proportion of physicians and medical students than of patients changed their preferences across the three graphs. Patients appeared to use information contained in five-year survival graphs in a different way than physicians and medical students, minimizing or neglecting the importance of ele ments of the five-year survival curve other than immediate (year 0) and long-term (year 5) survival data when presented with curve areas of differing sizes, while the physicians reported using intermediate (year 2 to year 4) data as well as curve shape. Key words: cognitive biases; framing effect; informed consent; medical decision making; preference; five-year survival; life expectancy. (Med Decis Making 1993;13:59-63)