Does the choice of tariff matter?

There is an increasing trend globally to develop country-specific tariffs that can theoretically better reflect population's preferences on health states for preference-based health-related quality-of-life instruments, also known as multiattribute utility instruments. This study focused on the most recently developed 5-level version of EuroQol-5 Dimension (EQ-5D) questionnaire, 1 of the world's most well-known multiattribute utility instruments, and aimed to empirically explore the agreements and known-group validities of applying the country-specific tariff versus tariffs developed from other countries using a sample of psoriasis vulgaris patients in Mainland China.A convenience sampling framework was adopted to recruit patients diagnosed with psoriasis vulgaris from Xiangya Hospital, Central South University, China, between May 2014 and February 2015. The 5-level EuroQol-5 dimensions (EQ-5D-5L) utilities were scored by using the Chinese, Japanese, and UK tariffs. Health state utilities were compared using a range of nonparametric test. The intraclass correlation coefficients and Bland-Altman plots were used to examine the agreements among the 3 EQ-5D-5L scores. Health state utility decrements between known groups were investigated using both effect size and a regression analysis.In all, 350 patients (aged 16 years or older) were recruited. There were significant differences among the 3 national tariff sets. Overall, 3 tariffs showed excellent agreements (intraclass correlation coefficient >0.90); however, the wide limits of agreement from the Bland-Altman plots suggest that these tariffs cannot be used interchangeably. The EQ-5D-5L scores using the Chinese-specific tariff showed the best known-group validity than the other 2 tariffs in this Chinese patient sample. The evidence from this study supports the choice of the country-specific tariff to be used in Mainland China.