Examining the relationship between the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS) and EQ-5D-5L and comparing their psychometric properties.

BACKGROUND: The purpose of this study is to examine the relationship between the Short Warwick-Edinburgh Mental Well-being Scale (SWEMWBS) and EQ-5D-5L and compare their psychometric properties in 4 chronic conditions in China.

METHODS: Participants were invited to complete the online survey. Spearman's rank correlation was used to evaluate the correlation between SWEMWBS and EQ-5D-5L; exploratory factor analysis was used to ascertain the number of unique underlying latent factors measured by SWEMWBS and EQ-5D-5L. Next, we assessed the psychometric properties of SWEMWBS and EQ-5D-5L by reporting distributions and examining their known-group validity and convergent validity.

RESULTS: In total, 500 individuals participated the online survey. Spearman's rank correlation showed that EQ-5D-5L dimensions, except for the anxiety/depression dimension, were weakly correlated with all dimensions of SWEMWBS. The two-factor solution for exploratory factor analysis found that all of SWEMWBS dimensions loaded onto one factor, four EQ-5D-5L dimensions (mobility, self-care, usual activities and pain/discomfort) onto another, and the EQ-5D-5L item of anxiety/depression item loaded moderately onto both factors. Patients of four disease groups had different distributions of responses for both SWEMWBS and EQ-5D-5L. In terms of known-group validity, both the F statistic and AUROC value of EQ-5D-5L utility scores were significantly higher than SWEMWBS scores in all four pair-wised comparisons. The Pearson correlation coefficient between EQ-5D-5L utility scores, SWEMWBS scores and EQ-VAS was 0.44 (P < 0.01) and 0.65 (P < 0.01), respectively.

CONCLUSIONS: SWEMWBS and EQ-5D-5L measure different constructs and can be seen as complementary measures. Both measures demonstrated good convergent validity and known-group validity with EQ-5D-5L being a more sensitive measure, even for mental conditions.