Comparison of EQ-5D-5L health state utilities using four country-specific tariffs on a breast cancer patient sample in mainland China

OBJECTIVE The objective of this study was to compare the differences in the five-level EuroQol-5 dimensions (EQ-5D-5L) health state utility scores derived from Chinese, Japanese, Korean, and UK tariffs. METHODS Six hundred and twenty-one breast cancer patients were invited for a face-to-face interview in Qingdao Municipal Hospital, China. EQ-5D-5L was scored using tariffs from China, Japan, Korea, and the UK. The null hypothesis of normal distribution of the EQ-5D-5L utility score was tested by the Shapiro-Wilk test. Nonparametric Friedman test and Wilcoxon signed-rank test were used to determine the difference among the four tariffs. The intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to study the agreement among the four EQ-5D-5L scores. Known-groups validity was studied using a regression framework. RESULTS There were 608 participants in the final analysis, with a mean ± standard deviation (SD) age of 48.0±9.6 years. EQ-5D-5L utility scores were non-normally distributed. The means (median) ± SD of EQ-5D-5L utilities derived from Chinese, Japanese, Korean, and UK tariffs were 0.828 (0.879) ±0.184, 0.802 (0.823) ±0.164, 0.831 (0.829) ±0.137, and 0.838 (0.866) ±0.154, respectively. Among pairwise comparisons, the difference of median EQ-5D-5L utility scores was only insignificant between Chinese and UK tariffs. Excellent agreements (with ICCs >0.9) were found among the four tariffs albeit the limits of agreement between each pair of tariffs were wide. Known-groups validity was supported. CONCLUSION Although four country-specific EQ-5D-5L tariffs have shown an overall high level of correlation and agreement, none of them could be regarded as interchangeable. The higher correlation and agreement between Chinese and UK tariffs may be due to the similar functions that were used in the tariff development. In the absence of Chinese-specific tariff, the UK tariff is the second-best option to be applied in the Chinese population. Results of this study further contribute to the explanation of variations among country-specific tariffs.