title: Prevalence and Characteristics of Autism Spectrum Disorder Among 4-Year-Old Children in the Autism and Developmental Disabilities Monitoring Network.
abstract: OBJECTIVE
  Early identification of children with autism spectrum disorder (ASD) facilitates timely access to intervention services. Yet, few population-based data exist on ASD identification among preschool-aged children. The authors aimed to describe ASD prevalence and characteristics among 4-year-old children in 5 of 11 sites participating in the 2010 Autism and Developmental Disabilities Monitoring Network.
  
  
  METHODS
  Children with ASD were identified through screening of health and education records for ASD indicators, data abstraction and compilation for each child, and clinician review of records. ASD prevalence estimates, ages at first evaluation and ASD diagnosis, cognitive test scores, and demographics were compared for 4-year-old children and 8-year-old children living in the same areas.
  
  
  RESULTS
  Among 58,467 children in these 5 sites, 4-year-old ASD prevalence was 13.4 per 1000, which was 30% lower than 8-year-old ASD prevalence. Prevalence of ASD without cognitive impairment was 40% lower among 4-year-olds compared with 8-year-olds, but prevalence of ASD with cognitive impairment was 20% higher among 4-year-olds compared with 8-year-olds. Among 4-year-olds with ASD, female and non-Hispanic white children were more likely to receive their first comprehensive evaluation by age 36 months compared with male and non-Hispanic black children, respectively. Among children diagnosed with ASD by age 48 months, median age at first comprehensive evaluation was 27 months for 4-year-olds compared with 32 months for 8-year-olds.
  
  
  CONCLUSIONS
  Population-based ASD surveillance among 4-year-old children provides valuable information about the early identification of children with ASD and suggests progression toward lowering the age of first ASD evaluation within participating Autism and Developmental Disabilities Monitoring communities.
authors.affiliation: *Division of Birth Defects and Developmental Disabilities, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA; †Department of Psychiatry, University of Utah, Salt Lake City, UT; ‡Department of Pediatrics, Rutgers-New Jersey Medical School, Newark, NJ; §Department of Pediatrics, University of Arizona, Tucson, AZ; ‖Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI; ¶Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; **Waisman Center, University of Wisconsin-Madison, Madison, WI; ††Department of Psychiatry, Washington University School of Medicine, St Louis, MO.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Christensen
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Bilder
authors.forename: Walter
authors.initials: W
authors.lastname: Zahorodny
authors.forename: Sydney
authors.initials: S
authors.lastname: Pettygrove
authors.forename: Maureen S
authors.initials: MS
authors.lastname: Durkin
authors.forename: Robert T
authors.initials: RT
authors.lastname: Fitzgerald
authors.forename: Catherine
authors.initials: C
authors.lastname: Rice
authors.forename: Margaret
authors.initials: M
authors.lastname: Kurzius-Spencer
authors.forename: Jon
authors.initials: J
authors.lastname: Baio
authors.forename: Marshalyn
authors.initials: M
authors.lastname: Yeargin-Allsopp
mesh_terms: D000067877:Autism Spectrum Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D042241:Early Diagnosis; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D014481:United States / Q000453:epidemiology