Adolescents With Autism Spectrum Disorder: Diagnostic Patterns, Co-occurring Conditions, and Transition Planning.

Purpose: The objectives of this study were to describe child characteristics associated with later autism spectrum disorder (ASD) identification and the health status and educational transition plans of adolescents with ASD.

Methods: Longitudinal population-based surveillance cohort from the Autism Developmental Disabilities Monitoring Network during 2002-2018 in five catchment areas in the United States. Participants included 3,148 children born in 2002 whose records were first reviewed for ASD surveillance in 2010.

Results: Of the 1,846 children identified in the community as an ASD case, 11.6% were first identified after age 8 years. Children who were more likely to have ASD identified at older ages were Hispanic; were born with low birth weight; were verbal; had high intelligence quotient or adaptive scores; or had certain co-occurring neuropsychological conditions by age 8 years. By age 16 years, neuropsychological conditions were common with more than half of the adolescents with ASD having a diagnosis of attention-deficit/hyperactivity disorder or anxiety. Intellectual disability (ID) status was unchanged for the majority (>80%) of children from ages 8-16 years. A transition plan was completed for over 94% of adolescents, but disparities were observed in planning by ID status.

Discussion: A high percentage of adolescents with ASD have co-occurring neuropsychological conditions, markedly higher than at age 8. While most adolescents had transition planning, this occurred less often for those with ID. Ensuring access to services for all people with ASD during adolescence and transition to adulthood may help to promote overall health and quality of life.