Agreement among four diagnostic instruments for autism spectrum disorders in toddlers.

Autistic spectrum disorders (ASD) can be difficult to diagnose in toddlers. This study compared diagnostic measures (ADOS-G, ADI-R, CARS, and clinical judgment using DSM-IV criteria) applied to toddlers. Results indicated that the ADOS-G, CARS, and clinical judgment agreed with each other but not with the ADI-R. Many of the children classified with ASD by the other measures were not classified with autism by the ADI-R because they did not display enough repetitive behaviors and stereotyped interests. These results indicate that young children with ASD may not display repetitive behaviors and stereotyped interests, and for toddlers, the ADI-R would have a higher sensitivity if revised to include a diagnosis of PDD-NOS, for which the requirement of repetitive behaviors is less stringent.