The English and Chinese versions of the five-level EuroQoL Group's five-dimension questionnaire (EQ-5D) were valid and reliable and provided comparable scores in Asian breast cancer patients.
OBJECTIVE
To examine the measurement properties of and comparability between the English and Chinese versions of the five-level EuroQoL Group's five-dimension questionnaire (EQ-5D) in breast cancer patients in Singapore.


METHODS
This is an observational study of 269 patients. Known-group validity and responsiveness of the EQ-5D utility index and visual analog scale (VAS) were assessed in relation to various clinical characteristics and longitudinal change in performance status, respectively. Convergent and divergent validity was examined by correlation coefficients between the EQ-5D and a breast cancer-specific instrument. Test-retest reliability was evaluated. The two language versions were compared by multiple regression analyses.


RESULTS
For both English and Chinese versions, the EQ-5D utility index and VAS demonstrated known-group validity and convergent and divergent validity, and presented sufficient test-retest reliability (intraclass correlation = 0.72 to 0.83). The English version was responsive to changes in performance status. The Chinese version was responsive to decline in performance status, but there was no conclusive evidence about its responsiveness to improvement in performance status. In the comparison analyses of the utility index and VAS between the two language versions, borderline results were obtained, and equivalence cannot be definitely confirmed.


CONCLUSIONS
The five-level EQ-5D is valid, responsive, and reliable in assessing health outcome of breast cancer patients. The English and Chinese versions provide comparable measurement results.
Center for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore. chunfan.lee@scri.edu.sg
Chun Fan
CF
Lee
Raymond
R
Ng
Nan
N
Luo
Nan Soon
NS
Wong
Yoon Sim
YS
Yap
Soo Kien
SK
Lo
Whay Kuang
WK
Chia
Alethea
A
Yee
Lalit
L
Krishna
Celest
C
Wong
Cynthia
C
Goh
Yin Bun
YB
Cheung
D044466:Asian People / Q000523:psychology; D001943:Breast Neoplasms / Q000208:ethnology; D005260:Female; D006304:Health Status; D006801:Humans; D007802:Language; D008875:Middle Aged; D015999:Multivariate Analysis; D011594:Psychometrics; D011788:Quality of Life; D012044:Regression Analysis; D015203:Reproducibility of Results; D012846:Singapore; D011795:Surveys and Questionnaires