Evidence of item bias in a national flourishing measure for autistic youth.

Flourishing is a positive health indicator that aligns with strengths-based perspectives and measures within autism research. Flourishing indicators were recently included in the National Survey of Children's Health (NSCH) and have been used to evidence disparities in flourishing experienced by autistic children compared to non-autistic peers. Yet, little has been done to examine the utility of standard flourishing items for this population. This study examined the NSCH caregiver-reported flourishing items for measurement item bias. A cross-sectional, representative sample of autistic and non-autistic US children aged 6-17 years (n = 41,691) was drawn from the 2018-2019 NSCH public dataset. A confirmatory factor analysis using a multiple indicators and multiple causes model (MIMIC-CFA) was conducted to (1) test for differential item functioning (DIF; i.e., measurement bias); and (2) estimate latent mean group differences after controlling for DIF. Findings supported a 3-factor (social competence, school motivation, and behavioral control), 10-item model structure consistent with past literature, yet measurement bias was evident for 6 of the 10 items. Persistent group differences, after accounting for DIF and covariates, indicates that caregivers of autistic children perceive their children are experiencing meaningfully lower flourishing outcomes compared to caregivers of non-autistic children. However, evidence of measurement bias for items related to the social competence dimension calls into question the applicability of this measure for autistic children. Further interpretation of group differences and use of this measure should be approached with caution.