567 - Early Versus Delayed Diagnosis of Autism Spectrum Disorder

Poster Number: 567
Publication Number: 567.109

Sara G. Shank, Baylor College of Medicine, Houston, TX, United States; Sonia Monteiro, Texas Children's Hospital, Houston, TX, United States; Holly K. Harris, Baylor College of Medicine / Texas Children's Hospital, Houston, TX, United States; Robert G. Voigt, Ochsner Hospital for Children, Jefferson, LA, United States

Background: The average age at diagnosis of autism spectrum disorder (ASD) is 4 years, 2 months, with 25% of children not receiving an evaluation prior to 8 years of age. Socioeconomic factors and severity of symptom expression may impact the age of diagnosis. Given the importance of early intervention, understanding which factors may contribute to a delayed diagnosis is critical.

Objective: To determine if there are differences in socio-demographics, medical history, and verbal/nonverbal functioning at the time of evaluation for children diagnosed with autism spectrum disorder at an early age (2 to 3 years, 11 months) compared to children diagnosed at a later age (8 to 12 years).

Design/Methods: The electronic medical records of children evaluated in 2019 at a tertiary autism center and who received a new diagnosis of ASD were retrospectively reviewed. Data, including patient demographics, birth history, prior developmental-behavioral diagnoses, performance on developmental testing at time of evaluation, and final diagnoses were abstracted. For categorical variables, a chi-square test was run. For continuous variables an (unpaired) t test was used to compare groups.

Results: Children 2 to 3 years, 11 months of age (N=111) were compared to children 8-12 years of age (N=32). There were no differences in sociodemographic factors, including sex, race, ethnicity, language, parental education, or insurance status. Children diagnosed at 2 to 3 years, 11 months of age were more likely to be first born (54% vs. 37%, P=0.0045). Children diagnosed at 2 to 3 years, 11 months of age were more likely to have impaired (developmental quotient or standard score < 70) language/verbal reasoning (90% vs 48%, P=< 0.001) and nonverbal reasoning (48% vs 19%, P=0.011) compared to 8-12 year olds. Of the 8-12 year olds, 75% had a prior neurodevelopmental or mental health diagnosis (N=28) (38% had Language Disorder (N=12), 47% had ADHD (N=15), 31% had a mood or anxiety disorder (N=10) and 13% had Intellectual Disability (N=4)), and 53% had a school qualification of autism (N=17).

Conclusion(s): Children diagnosed with autism at a young age are more likely to have impaired verbal and nonverbal functioning compared to children identified at later ages. In our sample, sociodemographic characteristics did not influence timing of diagnosis. Our results suggest that mental health and other neurodevelopmental diagnoses may contribute to diagnostic overshadowing when identifying children with autism.