Early Assessment of Autism Spectrum Disorders: Correlation Between M-CHAT-R and ASD Diagnosis in a Portuguese Sample

Background:  Autism Spectrum Disorders (ASD) screening is not yet a common procedure in pediatric settings in Portugal. In order to promote ASD screening, using a tool validated in other countries, one M-CHAT-R study has been started with the collaboration with Georgia State University; preliminary findings are presented.

Objectives:  This study proposes to correlate M-CHAT-R scores with outcomes of diagnostic instruments used in ASD assessment, identify the more frequently reported items in the M-CHAT-R questionnaire, and evaluate the percentage of false negatives in a sample of toddlers diagnosed with ASD.

Methods:  Parents of children referred for early interventions services completed the M-CHAT-R questionnaire before they started their children assessment (n=31).  Their ages were between 20 and 30 months (m=24.90, SD=2.96). All the children in this sample completed an evaluation using ADOS, ADI-R and Griffiths Mental Development Scale and they were all diagnosed with ASD.

Results:  Total M-CHAT-R results were significantly related to ADI-R Reciprocal Social Interaction score (r=.856, p<.001) and ADI-R Communication score (r=.642, p<.001), but not Restricted, Repetitive Behaviors (p>.207). Analyzing ADOS scores, a significant relationship was found between total M-CHAT-R score and ADOS Communication score (r=.698, p<.001), Reciprocal Social Interaction score (r=.730, p<.001), Play score (r=.731, p<.001) and Stereotyped Behaviors and Restricted Interests score (r=.581, p<.001). Item analysis of M-CHAT-R results also highlighted 4 items pertaining to pointing and joint attention that were failed by more than 83% of the children with ASD. Finally, 96.8% of the sample screened positive on the M-CHAT-R, meaning that just 3.2% were a false negative.

Conclusions:  Results suggest that M-CHAT-R is a good instrument for identifying early symptoms of autism, indicated by the strong correlations with scores from ASD diagnostic instruments. Although is was not used as a screening tool, the small percentage of false negatives indicates that most of the children with ASD will present a positive M-CHAT-R and the higher the total M-CHAT-R score is, the more severe the ASD symptoms will probably be. The study will continue in order to get a larger sample and continue to reach more relevant conclusions for Portuguese context.