Characteristics of Toddlers Screening False Positive on the Modified Checklist for Autism in Toddlers (M-CHAT)

Background:  Early identification of young children with autism creates opportunity for early intervention to improve outcome.  Autism screening instruments have been shown to be useful in identifying children needing further evaluation for autism, but use of these instruments has also led to concern about the frequency of false positives that occur as part of the process.  False positives can create unnecessary stress for parents and lead to expensive and time consuming diagnostic evaluations.

Objectives: This study sought to identify characteristics of young children identified as at risk for autism, based on screening with the Modified Checklist for Autism in Toddlers (M-CHAT), but who were later found to not have an autism spectrum disorder based on a multidisciplinary evaluation.  Recognition of characteristics unique to this false positive group may be useful for improving the ability of screening instruments to distinguish young children with autism from those children with developmental delays and behavior problems but not autism. 

Methods:  Retrospective data from a state-wide early intervention program was analyzed comparing characteristics of children (ages 16 to 35 months) who screened positive for autism on the M-CHAT, but did not meet criteria for an autism spectrum disorder (N=122), to those with a positive screen and confirmed diagnosis of autism (N=69).

Results:  Children who turned out to not have an autism spectrum disorder despite screening positive had better fine motor skills and fewer feeding problems than children with confirmed autism.  Those with a false positive screen did not differ from those confirmed to have autism in measures of cognitive ability, adaptive behavior, or language skills.  

Conclusions:  Consideration of feeding issues and fine motor skills in the screening for autism, in conjunction with social communication skills currently included in the M-CHAT, may improve screening for autism in young children by reducing false positives.  This improvement in screening will benefit parents by reducing stress associated with a positive screen for autism and by reducing costs and time associated with diagnostic evaluations.