title: The discriminative power of the EuroQol visual analog scale is sensitive to survey language in Singapore.
abstract: BACKGROUND
  Existing evidence for validity of the visual analog scale of the EQ-5D-3L questionnaire (EQ-VAS) is weak in Chinese-speaking respondents in Singapore. We therefore investigated the validity of the Chinese (Singapore) version of EQ-VAS in patients with diabetes.
  
  
  METHODS
  In a cross-sectional survey, patients with type 2 diabetes seen in a primary care facility completed an identical Chinese or English questionnaire containing the EQ-5D-3L and questions assessing other health and disease-related characteristics. Convergent and known-groups validity of the EQ-VAS was examined for Chinese- and English-speaking respondents separately.
  
  
  RESULTS
  The EQ-VAS was correlated with the EQ-5D-3L health index and a 5-point Likert-type scale for assessing global health in both Chinese-speaking (N = 335) and English-speaking respondents (N = 298), suggesting convergent validity. The mean EQ-VAS scores differed between English-speaking patients with differing duration of diabetes (< 10 years versus ≥ 10 years), comorbidity status (absence versus presence), and complications of diabetes (absence versus presence), providing evidence for known-groups validity. However, the EQ-VAS scores for Chinese-speaking respondents known to differ in these characteristics were similar, even among subgroups of relatively younger patients or those with formal school education.
  
  
  CONCLUSIONS
  Chinese- and English-speaking Singaporeans respond differently to the EQ-VAS. The Chinese version of EQ-VAS appears less sensitive than its English version for measuring global health in patient populations in Singapore.
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore. nan_luo@nuhs.edu.sg
authors.forename: Nan
authors.initials: N
authors.lastname: Luo
authors.forename: Sheng-Qun
authors.initials: SQ
authors.lastname: Cang
authors.forename: Hui-Min Joanne
authors.initials: HM
authors.lastname: Quah
authors.forename: Choon-How
authors.initials: CH
authors.lastname: How
authors.forename: Ee Guan
authors.initials: EG
authors.lastname: Tay
mesh_terms: D000368:Aged; D044466:Asian People / Q000523:psychology*; D002681:China / Q000208:ethnology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000453:epidemiology / Q000523:psychology*; D016002:Discriminant Analysis; D005260:Female; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000523:psychology; D011320:Primary Health Care; D011594:Psychometrics / Q000295:instrumentation; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D012846:Singapore / Q000453:epidemiology; D012923:Social Class; D011795:Surveys and Questionnaires / Q000592:standards*