Are Children's Self-Reports and Proxy-Reports of Health Utility Agreed? A School-Based Study in China using the EQ-5D-Y and CHU-9D

Objective: This study investigated a general Chinese child population aged 7–8 years with the EuroQol 5-Dimension Youth Version (EQ-5D-Y) and Child Health Utility 9D (CHU-9D) instruments, aiming to examine the agreement between self-reports and proxy-reports across various dimensions and overall health utility values, as well as to explore potential factors that may affect the agreement and utility values. Methods: Data were collected from second-grade students aged 7–8 in four schools in Guangxi and Guizhou provinces, China. Children and their proxies independently completed their respective versions of the questionnaires, including the EQ-5D-Y, the CHU-9D, and other socio-demographic information. The agreement between self-reports and proxy-reports in various dimensions was assessed using agreement rate and Adjusted Consistency (AC) value. Bland–Altman (BA) plots and Intraclass Correlation Coefficient (ICC) were utilized to analyze the agreement of utility values. Subgroup analyses of ICC and multiple linear regression analysis were conducted to explore factors influencing the agreement between self-reports and proxy-reports. Results: A total of 369 pairs of valid questionnaires were collected from both children and proxies. The AC values for various dimensions showed good agreement between children and proxies for physical function dimensions, but poorer agreement for subjective social and psychological function dimensions. BA plots revealed significant overestimation of children's utility values by both EQ-5D-Y and CHU-9D proxy-reports compared to self-reports. The ICC values for self-reported and proxy-reported utilities were 0.130 for the EQ-5D-Y and 0.295 for the CHU-9D. Subgroup analysis revealed that mothers had higher ICC values and better agreement with children compared to fathers. Moreover, children's health conditions, parental marital status, and family's highest education level impacted agreement results. Conclusions: For the general child population aged 7–8 years in China, the agreement between self-reported and proxy-reported utilities is weak, particularly in subjective social and psychological dimensions, with proxy-reports significantly overestimating children's utility values compared to self-reports. Self-reports and proxy-reports of health utility should be considered complementary rather than interchangeable. The findings provide valuable insights and references for the development of guidelines for self-reports and proxy-reports of children's utility instruments.