Comparison of the measurement properties between a short and generic instrument, the 5-level EuroQoL Group's 5-dimension (EQ-5D-5L) questionnaire, and a longer and disease-specific instrument, the Functional Assessment of Cancer Therapy-Breast (FACT-B), in Asian breast cancer patients.
OBJECTIVE
To compare the measurement precision and related properties between the 5-level EuroQoL Group's 5-dimension (EQ-5D-5L) questionnaire and the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire in assessing breast cancer patients.


METHODS
An observational study of 269 Singaporean breast cancer patients. To compare discriminative ability and responsiveness, the effect sizes (in standard deviation) of the EQ-5D-5L and the FACT-B in relation to health indicators and the change in performance status or quality of life were estimated. Test-retest reliability was examined using the intraclass correlation (ICC).


RESULTS
Using performance status, evidence of disease, and treatment status as the criteria, the differences (FACT-B minus EQ-5D-5L) in the effect size for discriminative ability were negative or closed to zero, and the 90% confidence intervals totally fell within the zone that indicated the non-inferiority of the EQ-5D-5L. For responsiveness and test-retest reliability, the confidence intervals of the differences in effect size and ICC overlapped the non-inferiority margin; thus, non-inferiority in these two aspects could neither be confirmed nor rejected.


CONCLUSIONS
The EQ-5D-5L was non-inferior to the FACT-B in discriminating breast cancer patients with different health conditions cross-sectionally. The EQ-5D-5L serves as a reasonable alternative or supplementary instrument to the FACT-B in assessing breast cancer patients' health outcomes.
Center for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore. chunfan.lee@scri.edu.sg
Chun Fan
CF
Lee
Nan
N
Luo
Raymond
R
Ng
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 / Q000523:psychology*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012846:Singapore; D011795:Surveys and Questionnaires