Factors Associated with a Delayed Autism Spectrum Disorder Diagnosis in Children Previously Assessed on Suspicion of Autism.

This study aimed to investigate factors associated with a delayed autism spectrum (ASD) diagnosis when compared to children with either no or early ASD diagnosis. Among 893 children assessed for ASD before age 8, 39% had no ASD at baseline, of which 21% received a later ASD diagnosis. Autism symptoms, diagnostic history of other developmental disorders, cognitive ability, and socioeconomic factors were associated with delayed ASD. Autism Diagnostic Observation Schedule (ADOS) scores in delayed ASD fell between early and no ASD. Other developmental disorders, time and clinical trends like ADOS use and low parental education distinguished delayed and early ASD, whereas higher frequency of IQ < 70 at baseline and a diagnosis of emotional disorders during follow-up distinguished delayed and no ASD.

Time Trends in Diagnostics and Clinical Features of Young Children Referred on Suspicion of Autism: A Population-Based Clinical Cohort Study, 2000-2010.

The present study aimed to explore clinical trends in the period 2000-2010, along with discriminating clinical factors for autism spectrum disorder (ASD), in young children suspected of ASD. The following trends were observed: (1) a rise in referrals including an increase in referrals among language-abled children, (2) an increase in children assigned an ASD diagnosis after assessment, and (3) a decrease in Autism Diagnostic Observation Schedule total score. The distribution of ASD subtypes and IQ level did not change. Results suggest that a higher proportion of children with less severe autism symptoms were referred and diagnosed. Further, restricted and repetitive behaviors seemed to be a key discriminating factor when distinguishing between ASD and no-ASD children with a discordant symptom profile.