COMPARISON OF TIME-TRADEOFF UTILITIES AND RATING-SCALE VALUES OF CANCER-PATIENTS AND THEIR RELATIVES - EVIDENCE FOR A POSSIBLE PLATEAU RELATIONSHIP

Because they are easy to administer, rating Scales are often used as p roxies for utility measures. The authors investigated the relationship between time-tradeoff utilities and rating scale values in two popula tions: 124 cancer patients asked to evaluate their current states of h ealth and 102 relatives and close friends of cancer patients asked to evaluate health-state scenarios. None of the models tested effectively described the relationship between individual patients' rating scale values and time-tradeoff utilities for their current states of health. In contrast, both a plateau and a power-function model explained the variability in the responses. of the relatives reasonably well (R(2) = 0.56 and R(2) = 0.58, respectively). Given that many respondents who were unwilling to trade off any time assigned rating scale values of w ell below 100, a plateau model may represent the best approach to adju sting rating scale values for health-state scenarios when it is not fe asible to elicit time-tradeoff utilities.