Measurement equivalence of the English, Chinese and Malay versions of the World Health Organization quality of life (WHOQOL-BREF) questionnaires

Table 2 WHOQOL-BREF scales: mean (SD) by language version, equivalence margin and adjusted difference between the two language versions

Scale	English (n = 428)	Chinese (n = 427)	Malay (n = 348)	Equivalence Margin^a	English vs Chinese Difference^b (90% CI)	English vs Malay Difference^b (90% CI)	Chinese vs Malay Difference^b (90% CI)
Scale	Mean (SD)	Mean (SD)	Mean (SD)	Equivalence Margin^a	English vs Chinese Difference^b (90% CI)	English vs Malay Difference^b (90% CI)	Chinese vs Malay Difference^b (90% CI)
Physical	74.6 (15.8)	71.7 (15.7)	72.3 (18.9)	±5	−1.4 (−3.1 to 0.3)^†	−0.4 (− 2.2 to 1.3)^†	− 1.0 (− 2.7 to 0.8)^†
Psychological	72.3 (14.3)	67.2 (16.0)	70.6 (14.0)	±5	−4.1 (−5.7 to − 2.5)^‡	− 0.5 (− 2.2 to 1.3)^†	−3.6 (− 5.4 to − 1.9)^‡
Social	73.5 (16.2)	68.9 (13.4)	74.1 (14.8)	±5	−3.8 (− 5.5 to − 2.2)^‡	1.4 (− 0.4 to 3.2)^†	−5.2 (− 7.0 to − 3.5)^‡
Environmental	71.8 (14.3)	68.2 (14.6)	68.7 (12.8)	±5	− 2.7 (− 4.2 to − 1.1)^†	−1.2 (− 2.9 to 0.4)^†	−1.4 (− 3.1 to 0.2)^†

^aApproximately 0.3 SD
^bEnglish minus Chinese, English minus Malay, and Chinese minus Malay, adjusted for age, sex, education, marital status, smoking status, chronic disease and body mass index
†Equivalence confirmed; ‡Equivalence inconclusive

ISSN: 1477-7525