Comparison of the psychometric properties of the EQ-5D-3L and SF-6D in the general population of Chengdu city in China

The EQ-5D-3L and SF-6D are the most commonly used economic evaluation instruments. Data comparing the psychometric properties of the instruments are scarce in the Chinese population. This study compared the psychometric properties of these measures in the Chinese general population in Chengdu. From October to December 2012, 2186 respondents (age ≥18) were selected from urban and rural areas of Chengdu, China, via multistage stratified cluster sampling. Correlations, scatter plots and Bland-Altman plots were used to explore the relationships between the 2 measures. Ceiling and floor effects were used to analyze the score distribution. The known-groups method was used to evaluate discriminant validity. Among 2186 respondents, 2182 completed the questionnaire, and 2178 (18–82 years old, mean 46.09 ± 17.49) met the data quality requirement. The mean scores for the EQ-5D-3L(CN), EQ-5D-3L(UK), and SF-6D(UK) were 0.95 (Std: 0.11), 0.93 (Std: 0.15), and 0.79 (Std: 0.12), respectively. The correlations between domains ranged from 0.16 to 0.51. The correlation between the EQ-5D-3L(CN) and SF-6D(UK) and between the EQ-5D-3L(UK) and SF-6D(UK) was 0.46. The scatter plots and Bland-Altman plots demonstrated poor agreement between the EQ-5D-3L and SF-6D. The floor and ceiling effects were respectively 0.05% and 74.60% for the EQ-5D-3L and 0.05% and 2.53% for the SF-6D(UK). The EQ-5D-3L(CN), EQ-5D-3L(UK) and SF-6D have good discriminant validity in different sociodemographic and health condition groups. The SF-6D has higher level of discriminant validity in moderately healthy groups in the EQ-5D-3L full-health population. Both the EQ-5D-3L and SF-6D are valid economic evaluation instruments in the Chinese general population in Chengdu but do not seem to be interchangeable. The EQ-5D-3L has a higher ceiling effect and higher level of discriminant validity among different sociodemographic groups, and the SF-6D has a lower ceiling effect and higher level of discriminant validity in health condition groups. Users may consider the evidence in the choice of these instruments.