Objective: Most autism spectrum disorder (ASD) screening measures have been developed for use with low-risk (LR) children; however, measures may perform differently in high-risk (HR) younger sibling populations. The current study sought to investigate the performance of an ASD screening measure, the Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-R/F), in a sample of HR younger siblings and directly compared its performance with that in an LR sample.
Methods: High-risk younger siblings (n = 187) and LR children (n = 15,848) were screened using the M-CHAT-R/F. Screen-positive children completed comprehensive evaluations. The M-CHAT-R/F psychometric properties and clinical characteristics were compared across the samples.
Results: The M-CHAT-R/F demonstrated a significantly higher screen-positive rate and ASD detection rate in the HR sample compared with the LR sample. Children with ASD in the HR sample had stronger verbal, nonverbal, and overall cognitive abilities compared with children with ASD in the LR sample despite comparable ASD severity and adaptive functioning. High positive predictive value of the M-CHAT-R at initial screen, with only incremental change after Follow-Up, suggests that Follow-Up is less critical in HR than LR samples. A significantly lower number of changed responses during Follow-Up further supports improved reporting accuracy of parents with ASD experience compared with parents less familiar with ASD.
Conclusion: The findings suggest that the M-CHAT-R/F can distinguish between ASD and non-ASD at 18 to 24 months in an HR sibling sample, with performance comparable with or better than its performance in the general population.