Instrument-Defined Estimates of the Minimally Important Difference for EQ-5D-5L Index Scores.

Abstract

The five-level EuroQol five-dimensional questionnaire (EQ-5D-5L) is a preference-based measure of health-related quality of life (HRQOL), which yields an index score anchored at 0 (dead) and 1 (full health). We lack evidence on estimates for the minimally important difference (MID) of the EQ-5D-5L that will help in interpreting differences or changes in HRQOL measured by this scale score. To estimate the MID of the EQ-5D-5L index score for available scoring algorithms including algorithms from Canada, China, Spain, Japan, England, and Uruguay. A simulation-based approach based on instrument-defined single-level transitions was used to estimate the MID values of the EQ-5D-5L for each country-specific scoring algorithm. The simulation-based instrument-defined MID estimates (mean ± SD) for each country-specific scoring algorithm were as follows: Canada, 0.056 ± 0.011; China, 0.069 ± 0.007; Spain, 0.061 ± 0.008; Japan, 0.048 ± 0.004; England, 0.063 ± 0.013; and Uruguay, 0.063 ± 0.019. Differences in MID estimates reflect differences in population preferences, in valuation techniques used, as well as in modeling strategies. After excluding the maximum-valued scoring parameters, the MID estimates (mean ± SD) were as follows: Canada, 0.037 ± 0.001; China, 0.058 ± 0.005; Spain, 0.045 ± 0.009; Japan, 0.044 ± 0.004; England, 0.037 ± 0.008; and Uruguay, 0.040 ± 0.010. Simulation-based estimates of the MID of the EQ-5D-5L index score were generally between 0.037 and 0.069, which are similar to the MID estimates of other preference-based HRQOL measures.