Screening Measures and Diagnostic Outcomes in Young Children Evaluated for An Autism Spectrum Disorder

Background: While there is an increased awareness and demand for effective screening tools for young children at risk for ASD, there is not yet consensus on which measures are most effective. The M-CHAT and CSBS-ITC have not been investigated as closely among children who are referred for evaluation due to known or suspected developmental delays. Based on our previous research with these tools, the exploration of screening outcomes relative to diagnosis will be explored.

Objectives: To evaluate the relation of two screening measures for identifying young children with possible ASD with the outcome clinical diagnosis, including:

(1) What is the diagnosis of children with positive and negative screening outcomes on the M-CHAT?

(2) What is the diagnosis of children with positive and negative screening outcomes on the CSBS-ITC?   

Methods: As part of the intake process for referred children under the age of 4 years, caregivers completed the CSBS-ITC and M-CHAT in addition to a general intake questionnaire. Final diagnoses were concluded by members of the interdisciplinary team.

Results: 145 children were screened using the M-CHAT and have final clinical diagnosis decisions and 137 children were screened using the CSBS-ITC and have final clinical diagnosis decisions.  Of the children who failed the M-CHAT screening, 35% had a final diagnosis of ASD, 20% had a diagnosis of MDD, 22% had a diagnosis Mixed Receptive/Expressive Language Delay (MRec/Exp), 16% had a diagnosis of other DD, and 7% had a diagnosis of Typical Development (TD).  Further, of the children who failed the M-CHAT, 39 of the 45 children in the ASD group or 87% were identified; 22 of the 30 children in the MDD group or 73% were identified; 24 of the 33 children or 73% in the MRec/Exp group were identified; 18 of the 21 children or 86% in the other DD group were identified; and 8 of the 16 or 50% in the TD group were identified.  Of the children who failed the CSBS-ITC screening, 37% had a final diagnosis of ASD, 21% had a diagnosis of MDD, 22% had a diagnosis MRec/Exp, 12% had a diagnosis of other DD, and 8% had a diagnosis of TD.  Additionally, of the children who failed the CSBS-ITC, 40 of the 44 children in the ASD group or 91% were identified; 22 of the 26 children in the MDD group or 85% were identified; 23 of the 31 children or 74% in the MRec/Exp group were identified; 13 of the 20 children or 65% in the other DD group were identified; and 8 of the 16 or 50% in the TD group were identified.  

Conclusions: The current data suggests that positive screens on either the M-CHAT or the CSBS-ITC are indicative of children subsequently diagnosed with ASD more often than children with other DDs or typically developing children.  However, as has been demonstrated in previous research, both screening tools demonstrate difficulties in distinguishing ASDs from other DDs, especially mixed developmental delays and mixed receptive expressive language delays, at the screening level.