Relationship Between Screening Measures and Symptom Severity 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 show tremendous promise for use in primary care settings to identify toddlers at risk for ASD, but these 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, it would be important to identify how the M-CHAT and CSBS-ITC screening measures compare to the results of gold standard assessment tools of the ADOS and the ADI-R.

Objectives: To evaluate the relation of two screening measures for identifying young children with possible ASD with the outcome of the ADOS and the ADI-R, including:

(1) do scores on screening measures correlate with ADOS symptom severity and ADI-R domain total scores?

(2) do screening results predict ASD classification using the ADOS and ADI-R?  

(3) do ADOS severity scores differ among children identified as at risk on the screening measures versus low-risk children?

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 form requesting information about development. Final diagnoses utilized ADI-R/ADOS and were concluded by members of the interdisciplinary team.

Results: 158 children have been screened using these procedures, with current diagnostic outcome available for a subset (n = 46), including final diagnosis of ASD or other developmental disabilities. M-CHAT total scores were positively correlated with ADOS severity scores (r=.32, p<.05) and with ADI-R domain scores (r=.33 to .54, p<.05), such that both screening and assessment measures showed elevated ASD symptoms. A similar trend was noted with the CSBS-ITC, where the presence of positive social/communication skills was negatively correlated with ADOS severity scores (r=-.31, p<.05) and with ADI-R domain scores (r=-.59 to    -.42, p<.01). Among the children with an Autism Spectrum or Autism classification on the ADOS, 79% were detected with the M-CHAT and 91% were detected with the CSBS-ITC. Among the children with an Autism classification on the ADI-R, 94% were detected with the M-CHAT and 100% were detected with the CSBS-ITC. Children who failed the M-CHAT and CSBS-ITC screenings had a mean ADOS severity score of 5.8 (SD=2.74) and 5.9 (SD=2.6), respectively, compared to children who passed the M-CHAT and CSBS-ITC screenings with a mean ADOS severity score of 5.0 (SD=1.9) and 4.0 (SD=2.4), respectively. Evaluations will be completed on 50 additional children.

Conclusions: The current data suggests that there is a strong relation between brief, caregiver completed screening measures and more comprehensive observation and interview measures for young children with ASD and DD. Further, level of severity of ASD symptomatology does not seem to distort caregiver report of actual child behavior on screeners. Additional analyses with the complete sample will also address how screener and assessment outcomes relate to clinical diagnosis.