Measurement Invariance on the Nine-Item Avoidant/Restrictive Food Intake Disorder Screen (NIAS) by Age and Reporter Status: Comparing ARFID Symptoms Among Self-Reporting Adults and Adolescents and Parent Reports of Children and Adolescents

Objective: Self-report measures of ARFID symptoms (e.g., Nine-Item Avoidant/Restrictive Food Intake Disorder Screen [NIAS]) are used to assess symptom differences between groups. Measurement invariance techniques clarify if groups interpret a measure similarly, providing a foundation for examining group differences. Considering age and reporter status (e.g., parent vs. self-report), we investigated measurement invariance of the NIAS in (1) self-reporting adults vs. adolescents; (2) parent reports on children vs. adolescents; and (3) parent reports on adolescents vs. adolescent self-report. If measurement invariance was supported, we examined symptom differences. Methods: Data were from the ARFID Genes and Environment (ARFID-GEN) project. Results: Self-reporting adults vs. adolescents and parent reports of adolescents vs. adolescent self-report interpreted the NIAS similarly (measurement invariance was supported). Measurement invariance was not supported in parent reports on children vs. adolescents. Self-reporting adults reported higher appetite scores (i.e., lower appetite) than self-reporting adolescents at the subscale and item level on the NIAS. Although no subscales differences were identified between parent reports on adolescents and adolescent self-reports, parents reported more picky eating and lower appetite in adolescents than self-reporting adolescents at the item level on the NIAS. Discussion: Findings support using the NIAS to measure symptom differences in self-reporting adults vs. adolescents and in parent reports of adolescents vs. adolescent self-reports. Findings may be leveraged by researchers interested in maturational effects of ARFID symptoms in adolescents and adults via self-reports on the NIAS and clinicians interested in tracking the convergence of parent and adolescent NIAS reports while undergoing treatment for ARFID.