OBJECTIVES: To test the Chinese EQ-5D-Y-3L value sets and EQ-TIPS in a large sample of young patients with COVID-19 in China, and to compare the differences between EQ-5D-5L and EQ-HWB-S in parent carers and identify the spillover effects of children's COVID-19 infection on their parents.

METHODS: A longitudinal study was conducted on children aged 0-18 years with COVID-19 and their parents. Baseline and follow-up surveys were completed by 861 and 311 dyads, respectively. An additional 231 non-infected children were included as controls. Parents completed the EQ-TIPS, proxy EQ-5D-Y-3L, EQ-HWB-S, and EQ-5D-5L on a tablet. Children aged ≥6 years self-completed the EQ-5D-Y-3L. The analysis involved assessing known-groups validity, convergent validity, test-retest reliability, inter-rater agreement, and responsiveness of the EQ instruments.

RESULTS: Children with COVID-19 and their parents, particularly those with more severe disease or poorer overall health assessment, exhibited higher EQ-TIPS Level Sum Score (LSS) and lower EQ-5D-Y/EQ-HWB-S/EQ-5D-5L index scores and EQ VAS. EQ-5D-5L captured a broader range of child health conditions compared to EQ-HWB-S. Moderate to strong correlations were found between overlapping dimensions of EQ-5D-5L and EQ-HWB-S. The EQ measures demonstrated good reliability, with ICCs ranging from 0.702 to 0.866 for test-retest agreement and 0.653 to 0.823 for inter-rater agreement. EQ-TIPS exhibited the highest responsiveness to COVID-19 recovery or improved OHA (ES: 1.21 - 1.75). Proxy EQ-5D-Y outperformed the self-completed version, while EQ-5D-5L performed slightly better than EQ-HWB-S in terms of responsiveness. Both EQ-HWB-S and EQ-5D-5L could estimate spillover effects associated with a child's health condition.

CONCLUSIONS: The findings support the reliability, validity, and responsiveness of EQ-TIPS and EQ-5D-Y-3L in assessing health outcomes of young patients with COVID-19. EQ-HWB-S and EQ-5D-5L demonstrated strong performance, showing comparable construct validity and responsiveness. This highlights their potential for estimating the spillover effects related to a child's health condition in the context of COVID-19 infection.