Large-scale use of the modified checklist for autism in low-risk toddlers.

OBJECTIVE The purpose of the study was to examine use of the Modified Checklist for Autism in Toddlers (M-CHAT) as an autism-specific screening instrument in a large, geographically diverse pediatrics-based sample. METHODS The M-CHAT and the M-CHAT Follow-Up (M-CHAT/F) were used to screen 18,989 toddlers at pediatric well-child visits in 2 US geographic regions. Pediatricians directly referred children to ascertain potential missed screening cases. Screen-positive children received the M-CHAT/F; children who continued to screen positive after the M-CHAT/F received a diagnostic evaluation. RESULTS Results indicated that 54% of children who screened positive on the M-CHAT and M-CHAT/F presented with an autism spectrum disorder (ASD), and 98% presented with clinically significant developmental concerns warranting intervention. An M-CHAT total score cutoff of ≥3 identifies nearly all screen-positive cases, and for ease of scoring the use of only the M-CHAT total score cutoff is recommended. An M-CHAT total score of 7 serves as an appropriate clinical cutoff, and providers can bypass the M-CHAT/F and refer immediately to evaluation and intervention if a child obtains a score of ≥7. CONCLUSIONS This study provides empirical support for the utility of population screening for ASD with the use of the M-CHAT in a primary care setting. Results suggest that the M-CHAT continues to be an effective screening instrument for ASD when the 2-step screening process is used. The M-CHAT is widely used at pediatric offices, and this study provides updated results to facilitate use and scoring of the M-CHAT by clinical providers.