Changes of heart: the switch-value method for assessing value uncertainty.

BACKGROUND Medical choices often evoke great value uncertainty, as patients face difficult, unfamiliar tradeoffs. Those seeking to aid such choices must be able to assess patients' ability to reduce that uncertainty, to reach stable, informed choices. OBJECTIVE The authors demonstrate a new method for evaluating how well people have articulated their preferences for difficult health decisions. The method uses 2 evaluative criteria. One is internal consistency, across formally equivalent ways of posing a choice. The 2nd is compliance with principles of prospect theory, indicating sufficient task mastery to respond in predictable ways. METHOD Subjects considered a hypothetical choice between noncurative surgery and palliative care, posed by a brain tumor. The choice options were characterized on 6 outcomes (e.g., pain, life expectancy, treatment risk), using a drug facts box display. After making an initial choice, subjects indicated their willingness to switch, given plausible changes in the outcomes. These changes involved either gains (improvements) in the unchosen option or losses (worsening) in the chosen one. A 2 x 2 mixed design manipulated focal change (gains v. losses) within subjects and change order between subjects. RESULTS In this demonstration, subjects' preferences were generally consistent 1) with one another: with similar percentages willing to switch for gains and losses, and 2) with prospect theory, requiring larger gains than losses, to make those switches. CONCLUSION Informed consent requires understanding decisions well enough to articulate coherent references. The authors' method allows assessing individuals' success in doing so.