The authors declare that they have no competing interests.
NL conceptualized the paper, co-wrote the manuscript, and verified the data analysis. SQC analyzed the data and wrote the first draft of the paper. JHQ, CHH, and EGT contributed to data interpretation and manuscript refinement. All authors have read and approved the final version of the manuscript.
Existing evidence for validity of the visual analog scale of the EQ-5D-3L questionnaire (EQ-VAS) is weak in Chinese-speaking respondents in Singapore. We therefore investigated the validity of the Chinese (Singapore) version of EQ-VAS in patients with diabetes.
In a cross-sectional survey, patients with type 2 diabetes seen in a primary care facility completed an identical Chinese or English questionnaire containing the EQ-5D-3L and questions assessing other health and disease-related characteristics. Convergent and known-groups validity of the EQ-VAS was examined for Chinese- and English-speaking respondents separately.
The EQ-VAS was correlated with the EQ-5D-3L health index and a 5-point Likert-type scale for assessing global health in both Chinese-speaking (N = 335) and English-speaking respondents (N = 298), suggesting convergent validity. The mean EQ-VAS scores differed between English-speaking patients with differing duration of diabetes (< 10 years versus ≥ 10 years), comorbidity status (absence versus presence), and complications of diabetes (absence versus presence), providing evidence for known-groups validity. However, the EQ-VAS scores for Chinese-speaking respondents known to differ in these characteristics were similar, even among subgroups of relatively younger patients or those with formal school education.
Chinese- and English-speaking Singaporeans respond differently to the EQ-VAS. The Chinese version of EQ-VAS appears less sensitive than its English version for measuring global health in patient populations in Singapore.