Comparison of the measurement properties of the EQ-5D-5L and SF-6Dv2 among patients with diabetes in China

OBJECTIVE: To validate and compare the measurement properties of the EQ-5D-5L and SF-6Dv2 among patients with diabetes in China. METHODS: A quota sampling method was used to recruit a representative sample, social-demographic characteristics, self-reported EQ-5D-5L and SF-6Dv2 responses were collected through online survey. Test-retest reliability and the agreement between EQ-5D-5L and SF-6Dv2 utility values were assessed using the intraclass correlation coefficient (ICC) and the Bland-Altman plot. Hypotheses testing including convergent validity and known-group validity were examined using Spearman's rank correlation and effect sizes, respectively. Sensitivity was compared using relative efficiency and receiver operating characteristic. RESULTS: A total of 600 respondents (53.67% male; mean age 60 years; 90% type 2, 10% type 1 diabetes) were included in this study. A higher ceiling effect was observed for EQ-5D-5L than for SF-6Dv2 (10.5% vs. 0.5%). The mean (SD) utility was 0.771 (0.196) for EQ-5D-5L and 0.671 (0.153) for SF-6Dv2. Agreement between the two instruments was good with an ICC of 0.776. The ICC values for the test-retest analysis were 0.982 for EQ-5D-5L and 0.986 for SF-6Dv2 among the subgroup (N = 100). The Spearman's rank correlation (range: 0.312-0.661) indicated an acceptable convergent validity between the dimensions of EQ-5D-5L and SF-6Dv2. Hypotheses for known-group validity were fulfilled in both instruments. The EQ-5D-5L showed basically equivalent discriminative capacities with the SF-6Dv2 (ES: 0.92-2.08 vs. 1.03-2.05). The SF-6Dv2 had 14.7-445.8% higher efficiency than the EQ-5D-5L at revealing differences in self-reported health status, except for the group dichotomized by "very good, good, fair or bad versus very bad". CONCLUSIONS: EQ-5D-5L and SF-6Dv2 showed generally comparable reliability, validity, and sensitivity in this sample of Chinese patients with diabetes. However, the utility values derived from the two instruments differed, indicating that they may not be used interchangeably. Further research is needed to evaluate and compare their responsiveness.