PURPOSE: This study validated the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire with 3400 respondents living in Singapore.
METHODS: The ethnic composition was 76.1% Chinese, 12.3% Malay, 9.6% Indian, and 2% Others. The sample included adults with disabilities (28.9%), adults recovering from mental health issues (14%), and adults from the general population (57.1%). Questionnaires about health-related conditions, the effects of disability on everyday functioning (WHODAS 2.0), the WHOQOL-BREF, and add-on modules of QOL of people with disabilities (WHOQOL-DIS) and QOL of elders (WHOQOL-OLD) were administrated.
RESULTS: Confirmatory factor analysis supported a construct of QOL made of four domains, revealing good construct validity. The four domains predicted overall QOL and health satisfaction. Good internal consistency was evidenced by high alpha coefficients for the physical (.79), psychological (.82), social relationships (.81), and environment (.83) domains. Convergent validity was shown by moderate correlations between the different questionnaires measuring QOL (WHOQOL-BREF, WHOQOL-DIS, and WHOQOL-OLD), and discriminant validity by a lower correlation between the WHOQOL-BREF and disability. Convergent and divergent validity were also indicated by higher correlations between similar constructs across the different measures, and lower correlations between dissimilar constructs across measures, respectively. Concurrent validity was supported by showing that individuals with chronic medical conditions had lower QOL than individuals without chronic medical conditions.
CONCLUSIONS: The results showed that the WHOQOL-BREF has sound psychometric properties and can be used to measure QOL in Singapore.
