title: Comparison of Value Set Based on DCE and/or TTO Data: Scoring for EQ-5D-5L Health States in Japan.
abstract: The valuation study of the five-level version of the EuroQol five-dimensional questionnaire (EQ-5D-5L) involved composite time trade-off (cTTO) and a discrete choice experiment (DCE). The DCE scores must be anchored to the quality-of-life scale from 0 (death) to 1 (full health). Nevertheless, the characteristics of the statistical methods used for converting the EQ-5D-5L DCE results by using TTO information are not yet clearly known.
  
  
  
  To present the Japanese DCE value set of the EQ-5D-5L and compare three methods for converting latent DCE values.
  
  
  
  The survey sampled the general population at five locations in Japan. 1098 respondents were stratified by age and sex. To obtain and compare the value sets of the EQ-5D-5L, the cTTO and DCE data were analyzed by a linear mixed model and conditional logit, respectively. The DCE scores were converted to the quality-of-life scale by anchoring to the worst state using cTTO, mapping DCE onto cTTO, and a hybrid model.
  
  
  
  The data from 1026 respondents were analyzed. All the coefficients in the cTTO and DCE value sets were consistent throughout all the analyses. Compared with the cTTO algorithm, the mapping and hybrid methods yielded very similar scoring coefficients. The hybrid model results, however, produced a lower root mean square error and fewer health states with errors exceeding 0.05 than did the other models. The DCE anchored to the worst state overestimated the cTTO scores of almost all the health states.
  
  
  
  Japanese value sets based on DCE were demonstrated. On comparing the observed cTTO scores, we found that the hybrid model was slightly superior to the simpler methods, including the TTO model.
authors: Department of Health and Welfare Services, National Institute of Public Health, Wako, Japan. Electronic address: t.shiroiwa@gmail.com.
authors: Takeru
authors: T
authors: Shiroiwa
authors: School of Pharmacy, International University of Health and Welfare, Otawara, Japan.
authors: Shunya
authors: S
authors: Ikeda
authors: Department of Health Sciences, Niigata University of Health and Welfare, Niigata, Japan.
authors: Shinichi
authors: S
authors: Noto
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
authors: Ataru
authors: A
authors: Igarashi
authors: Department of Health and Welfare Services, National Institute of Public Health, Wako, Japan.
authors: Takashi
authors: T
authors: Fukuda
authors: Graduate School of Health Sciences, Okayama University, Okayama, Japan.
authors: Shinya
authors: S
authors: Saito
authors: Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu, Japan.
authors: Kojiro
authors: K
authors: Shimozuma
mesh_terms: D000328:Adult; D002755:Choice Behavior; D005260:Female; D006304:Health Status; D006801:Humans; D007564:Japan; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D057240:Patient Preference / Q000706:statistics & numerical data; D011788:Quality of Life; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: EQ-5D-5L; discrete choice experiment (DCE); preference; time trade-off (TTO)