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Does Being Bilingual in English and Chinese Influence Responses to Quality-of-Life Scales?

Thumboo, Julian FRCP*; Fong, Kok-Yong Mmed; Machin, David PhD§; Chan, Siew-Pang Cmath; Soh, Chang-Heok BSc; Leong, Keng-Hong FRCP*; Feng, Pao-Hsii MD*; Thio, Szu-Tien RN*; Boey, Mee-Leng MD*


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.

Research Design. 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.

Conclusion. 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.

*From the Department of Rheumatology and Immunology, and Clinical Epidemiology Unit, Tan Tock Seng Hospital, Singapore.

From the Department of Medicine, National University of Singapore, Singapore.

§From the Clinical Trials and Epidemiology Research Unit, Ministry of Health, Singapore.

Supported by the National Medical Research Council of Singapore (grant 0160/96) and Tan Tock Seng Hospital.

Address correspondence and reprint requests to: Dr. Julian Thumboo, Department of Medicine, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074. E-mail:

Received April 16, 2001; initial review June 5, 2001; accepted September 12, 2001.

(Med Care 2002;40:105-112)

© 2002 Lippincott Williams & Wilkins, Inc.