title: Cross-cultural measurement equivalence of the 5-level EQ-5D (EQ-5D-5L) in patients with type 2 diabetes mellitus in Singapore.
abstract: BACKGROUND
  This study aimed to assess the measurement equivalence of the 5-level EQ-5D (EQ-5D-5L) among the English, Chinese, and Malay versions.
  
  
  METHODS
  A convenience sample of patients with type 2 diabetes mellitus were enrolled from a public primary health care institution in Singapore. The survey questionnaire comprised the EQ-5D-5L and questions assessing participants' socio-demographic and clinical characteristics. Multiple linear regression models were used to assess the difference in EQ-5D-5L index (calculated using an interim algorithm) and EQ-visual analog scale (EQ-VAS) scores across survey language (Chinese vs. English, Malay vs. English, and Malay vs. Chinese). Measurement equivalence was examined by comparing the 90% confidence interval of difference in the EQ-5D-5L index and EQ-VAS scores with a pre-determined equivalence margin. Multiple logistic regression models were used to assess the response patterns of the 5 Likert-type items of the EQ-5D-5L across survey language.
  
  
  RESULTS
  Equivalence was demonstrated between the Chinese and English versions and between the Malay and English versions of the EQ-5D-5L index scores. Equivalence was also demonstrated between the Chinese and English versions and between the Malay and Chinese versions of the EQ-VAS scores. Equivalence could not be determined between the Malay and Chinese versions of the EQ-5D-5L index score and between the Malay and English versions of the EQ-VAS score. No significant difference was found in responses to EQ-5D-5L items between any languages, except that patients who chose to complete the Chinese version were more likely to report "no problems" in mobility compared to those who completed the Malay version of the questionnaire.
  
  
  CONCLUSIONS
  This study provided evidence for the measurement equivalence of the different language versions of EQ-5D-5L in Singapore.
authors.affiliation: Center for Surgery and Public Health, Brigham and Women's Hospital, Harvard Medical School, 1620 Tremont Street, Boston, MA, USA. yewang@research.bwh.harvard.edu.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.affiliation: SingHealth Polyclinics, 167 Jalan Bukit Merah, Singapore, Singapore. Tan.Ngiap.Chuan@singhealth.com.sg.
authors.forename: Ngiap-Chuan
authors.initials: NC
authors.lastname: Tan
authors.affiliation: SingHealth Polyclinics, 167 Jalan Bukit Merah, Singapore, Singapore. tay.ee.guan@singhealth.com.sg.
authors.forename: Ee-Guan
authors.initials: EG
authors.lastname: Tay
authors.affiliation: Singapore General Hospital, Outram Road, Singapore, Singapore. julian.thumboo@sgh.com.sg.|Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore, Singapore. julian.thumboo@sgh.com.sg.
authors.forename: Julian
authors.initials: J
authors.lastname: Thumboo
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, 12 Science Drive 2, Block MD 1, 117597, Singapore, Singapore. ephln@nus.edu.sg.
authors.forename: Nan
authors.initials: N
authors.lastname: Luo
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People / Q000523:psychology*; D003431:Cross-Cultural Comparison; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000523:psychology*; D005260:Female; D006304:Health Status; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011594:Psychometrics / Q000295:instrumentation; D011788:Quality of Life / Q000523:psychology*; D012846:Singapore / Q000453:epidemiology; D011795:Surveys and Questionnaires / Q000592:standards*