Valuing EQ-5D-5L: Comparing the Time Trade Off and Discrete Choice Experiment Valuation Methods

Background: Two elicitation approaches used to develop EQ-5D-5L value sets are the Time Trade Off (TTO) and Discrete Choice Experiment (DCE). The recommended international valuation protocol (the EQ-VT) includes both TTO and DCE without duration. However, DCE with duration (DCETTO) has also been used. The methods may lead to differences in value set characteristics, and it is important to compare the values generated. The aim of this study was to compare the EQ-VT and an online DCETTO protocol. Methods: Data were collected from 302 Australians. Sample A (n = 151) completed the EQ-VT followed by the DCETTO, and Sample B (n = 151) completed the DCETTO followed by the EQ-VT. The EQ-VT included 15 TTO and 14 DCE tasks, and the DCETTO included 15 tasks. Value sets were modelled using hybrid, conditional logit and preference heterogeneity models and the characteristics were compared. We also compared the DCETTO estimates to the actual TTO values. Self-reported acceptability questions were also assessed. Results: The methods led to differences in the value sets produced. The DCETTO value set had a wider range than TTO (where the worst health state had values of - 0.923 and - 0.342 respectively). The relative magnitude of values for the mildest health states differed between approaches. Pain/discomfort and anxiety/depression consistently had the largest decrement, but the order of the other dimensions varied. For the 86 states included in the TTO, the actual TTO value differed from the estimated DCETTO value by between 0.003 and 0.622. Both the TTO and DCE were acceptable to respondents. Discussion: This is the first study directly comparing three health state valuation methods using a within-person study design and accounting for potential ordering effects. Insights from the results will add to the evidence regarding similarities and differences between the methods. This will inform the future development of EQ-5D valuation protocols.