Effect of EuroQol-5 Dimension on Visual Analogue Scale in Korean Population

Kim, Seon Ha; Jo, Soo Jin; Jo, Min Woo

Abstract

BACKGROUND
The EuroQol-5 Dimension (EQ-5D) is the most frequently used questionnaire in cost-utility studies such as the quality-adjusted life year measure. Nevertheless, little attention has been paid to the relationship between an individual's visual analogue scale (VAS) score and EQ-5D dimensions. The objective of this study was to assess the relationship between the EQ-5D and VAS quality of life measures after adjusting for socio-demographic factors in the Korean general population.
METHODS
The Fourth Korea National Health and Nutrition Examination Survey, which is a national representative sample, was used to analyze the impact of the EQ-5D dimensions on the VAS. The known-group construct validity of the VAS was assessed by factors that included age, income and comorbidities. The ordinary linear regression models were applied to test for the effect of the EQ-5D dimensions after adjusting for socio-demographic and clinical factors.
RESULTS
We found that the VAS showed good construct validity. The VAS significantly declined as age increased, and as education and income levels decreased. VAS scores decreased for all EQ-5D dimensions as the response level rose. The explanatory power of the VAS increased from 23.0% in the first model, which included only the EQ-5D dimensions and levels, to 25.0% in the full model, which included socio-demographic and clinical factors.
CONCLUSIONS
While the EQ-5D dimensions were significant factors in determining the VAS, they did not, however, explain a sufficient amount of variance in the VAS. Further research is required on adding more dimensions to the EQ-5D preference-based instrument.