Item-Level Sex Differences in Autism Spectrum Disorder Measures: A MIMIC Model Analysis of ADOS-2 and ADI-R in a Referred Pediatric Sample

PURPOSE: The current study aimed to examine item-level sex differences in the diagnostic measures of ASD traits for children and adolescents referred for an ASD evaluation. By including all those referred for an ASD evaluation, the study aimed to include females who may be mis- or under-diagnosed by current ASD diagnostic procedures. METHODS: The sample included 458 children and adolescents who were referred for an ASD evaluation at a tertiary care clinic. In this sample, 118 individuals (25.8%) were female, 282 (61.6%) were diagnosed with ASD, and the average age was 6.67 years (SD = 3.65). Multiple indicator multiple cause (MIMIC) models were used to examine differential item functioning on the ADOS-2 and ADI-R. RESULTS: Results indicated differential item functioning on a small proportion of ADI-R items (e.g., Circumscribed Interests, Inappropriate Facial Expressions, Imaginative Play, Spontaneous Imitation of Actions) across content areas, whereas there were no item-level sex differences identified on the ADOS-2. CONCLUSIONS: These findings suggest nuanced sex differences in ASD trait presentation among children and adolescents presenting with concern for ASD, as measured by standard diagnostic assessment tools. Future research should continue to explore detailed patterns of sex differences in trait measurement using precise sampling and incorporating additional diagnostic instruments, as a well-informed understanding of sex differences in ASD trait presentation and measurement is critical for addressing the existing sex bias in ASD research and clinical settings. This understanding will help ensure appropriate ASD characterization, identification, and diagnosis.