Modeling patient decision-making: The role of base rate and anecdotal information

Guidelines for managing patient-physician relationships often stem from either paternalistic or shared decision-making perspectives. Despite a number of advantages shown for the shared decision-making model, questions remain as to whether lay people make the most optimal decisions about their health care. This study explored the influence of anecdotal and base-rate information on health-care decisions. Three hundred and seventeen undergraduates read two vignettes describing a fictitious disease, followed by a description of two potential treatment protocols. The comparison treatment was 50% effective and accompanied by an anecdote that described a patient whose treatment resulted in an ambiguous outcome. A second treatment was presented as 30, 50, 70, or 90% effective, and accompanied by an anecdote that described a patient whose treatment resulted in a positive, ambiguous, or negative outcome. Subjects weighted anecdotal information more heavily than base-rate, or statistical, information when the anecdotal information was clearly positive or negative. Subjects presented with ambiguous anecdotal information weighed base-rate information most heavily. Implications for enhancing patient decision-making are discussed.