title: Does being bilingual in English and Chinese influence responses to Quality-of-Life scales?
abstract: BACKGROUND
  It is not known if the inclusion of bilinguals affects the results of research using Quality-of-Life (QoL) scales.
  
  
  OBJECTIVE
  To determine the influence of bilingualism on responses to a QoL scale.
  
  
  METHODS
  In this cross sectional study, a population-based, disproportionately stratified random sample of monolingual and bilingual ethnic Chinese completed the Short-Form 36 Health Survey (SF-36) in English or Chinese (representing an alphabet and pictogram based language respectively). Cumulative logit regression models were used to assess the influence of bilingualism on SF-36 scores, while adjusting for the influence of questionnaire language and known determinants of QoL.
  
  
  RESULTS
  English or Chinese SF-36 versions were completed by 1331 and 1380 subjects respectively (49% female, aged 21-65 years, 1366 bilingual, 501 English monolingual, 844 Chinese monolingual), with response rates exceeding 85%. Fifty percent of subjects were bilingual. Bilinguals differed from monolinguals in known determinants of QoL, being younger, better educated, and having fewer chronic medical conditions, and had SF-36 scores up to 8 points higher than monolinguals. After adjusting for these differences, bilingualism did not influence scores for any of eight SF-36 scales, whereas questionnaire language influenced scores for four scales. Use of the English SF-36 was associated with higher scores for General Health, Vitality, Role Emotional and Mental Health Scales (odds ratios 1.35-1.41), though the magnitude of these odds ratios suggests this association may not be clinically important.
  
  
  CONCLUSIONS
  Bilingualism did not influence responses to a QoL scale in this large, population-based study of subjects fluent in an alphabet and/or pictogram based language.
authors.affiliation: Department of Rheumatology and Immunology, Tan Tock Seng Hospital, Singapore. mdctj@nus.edu.sg
authors.forename: Julian
authors.initials: J
authors.lastname: Thumboo
authors.forename: Kok-Yong
authors.initials: KY
authors.lastname: Fong
authors.forename: David
authors.initials: D
authors.lastname: Machin
authors.forename: Siew-Pang
authors.initials: SP
authors.lastname: Chan
authors.forename: Chang-Heok
authors.initials: CH
authors.lastname: Soh
authors.forename: Keng-Hong
authors.initials: KH
authors.lastname: Leong
authors.forename: Pao-Hsii
authors.initials: PH
authors.lastname: Feng
authors.forename: Szu-Tien
authors.initials: ST
authors.lastname: Thio
authors.forename: Mee-Leng
authors.initials: ML
authors.lastname: Boey
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D019303:Multilingualism; D011788:Quality of Life; D015203:Reproducibility of Results; D012846:Singapore; D011795:Surveys and Questionnaires