Acceptability of computerized visual analog scale, time trade-off and standard gamble rating methods in patients and the public

One technique to enhance patient participation in clinical decision making is formal measurement of preferences and values. Three commonly applied methods are a visual analog scale(VAS), the standard gamble(SG), and the time trade-off(TTO). We studied participants subjective experience using computer implementations these methods using scale we call the VIBE (for Value Instrument Battery--Evaluation) that measures four aspects of user acceptance (clarity, difficulty, reasonableness, and comfort level) Studies were performed in two groups: patients with HIV infection (n=75) and a convenience sample of the general public(n=640). In the patient study, VIBE scores appeared reliable (Cronbach s alpha of 0.739, 0.826, and 0.716, for VAS, SG, and TTO ratings, respectively.) Patients acceptance of the VAS the highest, followed by the TTO and the SG method (p<0.05 for all comparisons). Despite significant enhancements in computer software for measuring SG preferences, observed differences in acceptance between SG and VAS methods were replicated in the general public study (p<0.0001 for differences). The results suggest developers of clinical decision support systems should use VAS and TTO rating methods where these methods are theoretically appropriate.