Validation of the modified checklist for Autism in toddlers, revised with follow-up (M-CHAT-R/F).

OBJECTIVE This study validates the Modified Checklist for Autism in Toddlers, Revised with Follow-up (M-CHAT-R/F), a screening tool for low-risk toddlers, and demonstrates improved utility compared with the original M-CHAT. METHODS Toddlers (N = 16,071) were screened during 18- and 24-month well-child care visits in metropolitan Atlanta and Connecticut. Parents of toddlers at risk on M-CHAT-R completed follow-up; those who continued to show risk were evaluated. RESULTS The reliability and validity of the M-CHAT-R/F were demonstrated, and optimal scoring was determined by using receiver operating characteristic curves. Children whose total score was ≥ 3 initially and ≥ 2 after follow-up had a 47.5% risk of being diagnosed with autism spectrum disorder (ASD; confidence interval [95% CI]: 0.41-0.54) and a 94.6% risk of any developmental delay or concern (95% CI: 0.92-0.98). Total score was more effective than alternative scores. An algorithm based on 3 risk levels is recommended to maximize clinical utility and to reduce age of diagnosis and onset of early intervention. The M-CHAT-R detects ASD at a higher rate compared with the M-CHAT while also reducing the number of children needing the follow-up. Children in the current study were diagnosed 2 years younger than the national median age of diagnosis. CONCLUSIONS The M-CHAT-R/F detects many cases of ASD in toddlers; physicians using the 2-stage screener can be confident that most screen-positive cases warrant evaluation and referral for early intervention. Widespread implementation of universal screening can lower the age of ASD diagnosis by 2 years compared with recent surveillance findings, increasing time available for early intervention.