A Time Trade-off-derived Value Set of the EQ-5D-5L for Canada

Abstract

Background: The 5-level version of the EQ-5D (EQ-5D-5L) was recently developed. A number of preference-based scoring systems are being developed for several countries around the world.

Objective: To develop a value set for the EQ-5D-5L based on societal preferences in Canada.

Methods: We used age, sex, and education quota sampling from the general population from 4 cities across Canada. Composite time trade-off (cTTO) and traditional time trade-off (tTTO) were used as the main elicitation technique. A total of 86 EQ-5D-5L health states grouped into 10 blocks were valued using cTTO, whereas a subset of 18 severe states was also valued using tTTO. Participants meeting predefined inconsistency criteria were excluded from the analyses. For the value set development, we used tTTO and positive cTTO values, while censoring negative and zero cTTO values at zero. Models with the main effects presented using linear terms combined with various additional terms were estimated. The preferred model was selected based primarily on logically ordered coefficients, and secondly model fit.

Results: Of the 1209 participants who completed the interview, 136 met criteria that excluded them from the primary analyses. The demographics and socioeconomic status of the remaining 1073 participants were similar to the Canadian general population. The preferred model has 5 linear terms for the main effects, a term for level 4 or 5 for each dimension, and a term for the squared total number of level 4 or 5 beyond the first. For this preferred model, the health utilities ranged from -0.148 for the worst (55555) to 0.949 for the best (11111) EQ-5D-5L states.

Conclusions: This is the first TTO-based value set of the EQ-5D-5L for Canada. It can be used to support the health utility estimation in economic evaluations for reimbursement decision making in Canada.

FIGURE 1

Distribution of observed tTTO and cTTO values for the 86 health states. Red circle represents observed cTTO score, whereas green circle represents observed tTTO score. The size of the circle corresponds to the frequency of the observed score. cTTO indicates composite TTO; tTTO, traditional TTO; TTO, time trade-off.

FIGURE 2

Predicted utilities versus observed utilities for the 86 health states. The green reference line represents perfect prediction for observation. cTTO indicates composite TTO; MAE, mean absolute error; tTTO, traditional TTO; TTO, time trade-off.

FIGURE 3

Sensitivity analyses on the inclusion criteria and censoring. Blue line: “the preferred model” that includes participants meeting the inclusion criteria and censoring nonpositive cTTO values at zero. Green line: including all participants and censoring nonpositive cTTO values at zero. Brown line: including participants meeting the inclusion criteria and censoring only negative cTTO values at zero. Purple line: including all participants and censoring only negative cTTO values at zero. cTTO indicates composite time trade-off.