The effect of individually assessed preference weights on the relationship between holistic utilities and nonpreference-based assessment.

In the assessment of health-related quality of life, nonpreference-based methods usually show only moderate correlations with utility-based measures. One cause may be that patients assign different weights to the various domains of health-related quality of life, for which nonpreference-based methods usually do not allow. Utilities reflect a weighted sum of these domains. The aim of this study is to assess whether the relationship between utility-based methods and nonpreference-based measures improves through the use of individual importance weights for the various domains of health-related quality of life. For this purpose, weights were obtained from 41 early-stage breast cancer patients, both before and during treatment, for seven pre-selected health status attributes representing important domains of health-related quality of life during chemotherapy. The importance weights were combined with the level of functioning on the attributes. These scores were regressed against patients' utilities for their actually experienced health state during chemotherapy, measured by means of a visual analog scale (VAS), a time trade-off (TTO), and a standard gamble (SG). Before weighting, the seven attribute scores were more strongly related to TTO and SG utilities than the nonpreference-based questionnaires. However, when they were combined with the importance weights, only the correlation with the SG utilities improved, and only so with the importance weights obtained before chemotherapy. In this study, assigning individually assessed preference weights to self-reported level of functioning did not result in stronger relationships with utilities.