Purpose: Decision aids seek to inform patients to allow weighing of benefits and harms of treatment options and deliver decisions consistent with patient’s preferences. Unlike most goods and services, where markets facilitate the construction of stable preferences, evidence indicates that patients do not have inherently well formed values for much of health care, where the expected outcomes are unfamiliar. Theory suggests that true preference construction requires individuals to trade-off between different outcomes. We sought to review the use and type of explicit value clarification exercises in current decision aids and to assess how many use constrained exercises involving trade-offs.
Methods: The complete inventory of decision aids held by the Ottawa Hospital Research Institute was reviewed. For each decision aid an assessment was made of whether a value clarification exercise was included and, if it was, the type of value exercise. Constrained value clarification techniques contain some notion of sacrifice, e.g. a trade-off between at least two different attributes (e.g. benefit, harm or other characteristic). Non-constrained approaches include rating scales (where respondents rate the importance of each attribute), and weigh scales (where respondents indicate their agreement or disagreement with statements).
Results: A total of 304 decision aids (8 unavailable) covering 145 different decisions were reviewed. 217 (71%) decision aids explicitly included a value clarification component. None used a constrained exercise. The vast majority of those that sought value clarification (97%) used a rating scale (most commonly a 5-stars or likert scales) to establish attribute importance.
Conclusions: While the basis for providing value clarification exercises is strong, our findings show that exercises in current decision aids are based on unconstrained techniques not requiring trade-offs. The concern is that unconstrained techniques fail to support the construction of stable values for treatment outcomes that are unfamiliar to the patient, and if that is the case then such techniques used in decision aids may impede preference-driven patient decision making. While constrained exercises are recognized to be more difficult to understand and implement, the wide use of computers has led to their implementation in other fields of decision making. Areas for further research include: (a) the impact of value clarification exercises on patient choices; and (b) the feasibility of constrained techniques in decision aids, given their time and cognitive requirements.