Methodological similarities and variations among EQ-5D-5L value set studies: a systematic review

Objectives (1) To descriptively compare the selected elements of valuation methods for EQ-5D-5L value set studies, (2) to compare the characteristics of the value sets, and (3) to examine the associations between the selected elements of valuation methods and the EQ-5D-5L value sets. Methods A systematic literature search of EQ-5D-5L valuation studies from 1 January 2009 to 22 April 2021 was conducted in selected databases. Following the initial search, we also explored additional studies published during the completion of the final version of the manuscript. Similarities and variations for selected elements of valuation methods were descriptively compared. The relative importance of dimensions, utility decrements between the levels, and distribution of the utility scores were used to compare value sets. A meta-regression analysis examined the associations between the selected methodological elements and the utility scores and dimension levels of EQ-5D-5L. Results A total of 31 studies were included in this review. Methodological similarities centered around data collection and preference elicitation method. On the other hand, variations include sampling technique, sample size, and value set modeling. The variations in value sets based on the relative importance of dimension, decrement in utility score, and distribution of utility score across countries were observed. Although the distribution of the utility scores differed across countries, higher levels of each dimension tended to have a larger decrement in the utility scores. Mean utility scores for the experience-based value sets were higher than those estimated using stated choice methods. The selected methodological elements were not significantly associated with the mean predicted utility scores or most dimension-level coefficients. Conclusions EQ-5D-5L health state valuation methods and characteristics of value sets differed across studies. The impact of the variation of methodological elements on the value sets should be further investigated.