Testing culturally relevant EQ-5D-5L bolt-ons for the Chinese general population: first quantitative phase of a mixed methods study

As part of a large mixed-methods study, we aim to develop culturally relevant additional dimensions (bolt-ons) for the EQ-5D-5L in China. In the qualitative phase, we developed seven candidate bolt-ons. In this first quantitative phase, we aimed to test the psychometric properties of these bolt-ons in the Chinese adult general population.

Adding bolt-ons reduced the ceiling of the EQ-5D-5L by 2.3%-points (adaptation to society) to 7.6%-points (tiredness/lack of strength). Tiredness/lack of strength had the highest relative informativity (Shannon’s evenness index = 0.67). Appetite and social relationships showed the best divergent validity from the five core dimensions. Tiredness/lack of strength demonstrated strong or moderate correlations with SF-6Dv2 vitality (r = 0.648) and EQ-HWB-9 exhaustion (r = 0.541) dimensions. Adding tiredness/lack of strength, climate adaptation and emotional control improved the explanatory power for the EQ VAS score. Tiredness/lack of strength enhanced the known-groups validity for differentiating between respondents based on the presence of chronic diseases and in group comparisons by SF-6Dv2 level sum scores.

The tiredness/lack of strength bolt-ons performed best, but the sleep problems and appetite bolt-ons also improved several psychometric properties of the EQ-5D-5L in the Chinese general population. Combined with patient evidence, these findings may inform evidence-based bolt-on selection in the Chinese context.