CDC Report: Examining the Prevalence of Autism Among Children in the United States

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The prevalence of autism spectrum disorder varied across sites, from 13.1 to 29.3 per 1000 children.
The prevalence of autism spectrum disorder varied across sites, from 13.1 to 29.3 per 1000 children.

According to data from the Autism and Developmental Disabilities Monitoring Network published in Morbidity and Mortality Weekly Report Surveillance Summaries, the prevalence of autism spectrum disorder (ASD) among 11 study sites across the United States was 16.8 per 1000 children aged 8 years. This estimate is higher than previously reported and may indicate an increased need for therapeutic services among communities with high ASD prevalence.

The Autism and Developmental Disabilities Monitoring Network is an active surveillance system that provides estimates for the prevalence of ASD among children aged 8 years who reside within 11 specific study sites across the United States. Surveillance is a 2-phase procedure, involving first the abstraction of evaluations completed by service providers and then the systematic review of abstracted information by clinicians to determine ASD case status. 

A total cohort of 325,483 children were included in the analysis, and 5473 children met the ASD surveillance case definition for an overall prevalence of 1 in 59 children. ASD prevalence varied across sites, from 13.1 to 29.3 per 1000 children. ASD prevalence was significantly higher among boys than among girls at all 11 sites, for an overall male-to-female prevalence ratio of 4.5 (P <.01). According to combined data across all sites, the ASD prevalence among white children (17.2 per 1000) was 7% greater than among black children (16.0 per 1000) and 22% greater than in Hispanic children (14.0 per 1000).

Data on intellectual ability were reported for 9 states and indicated that 31% of children with ASD were also classified as having an intellectual disability (IQ ≤70); 25% were in the borderline range (IQ 71-85), and 44% had average to above average scores (IQ >85). These numbers varied by sex, with 36.3% of girls and 29.5% of boys meeting the criteria for intellectual disability (P <.01). Results could also be stratified by race/ethnicity, with 44% of black children classified in the range of intellectual disability, compared with 35% of Hispanic children and 22% of white children.

These data indicate an increased need for “behavioral, educational, residential, and occupational services” at various levels across the United States and emphasize the importance of research on the risk factors for ASD. Future surveillance efforts will expand geographically and capture additional social determinants of health to develop a more complete picture of ASD prevalence in the United States.

Reference

Baio J, Wiggins L, Christensen DL, et al. Prevalence of autism spectrum disorder among children aged 8 years - autism and developmental disabilities monitoring network, 11 sites, United States, 2014. MMWR Surveill Summ. 2018;67(6):1-23.

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