title: Autism spectrum disorders in preschool-aged children: prevalence and comparison to a school-aged population.
abstract: OBJECTIVE
  The purpose of this study was to determine the prevalence and case characteristics of children with autism spectrum disorders (ASDs) among 4-year-olds and to compare findings to previous prevalence estimates for 8-year-olds in the same geographic area.
  
  
  METHODS
  South Carolina (SC) has been a participant in the Centers for Disease Control and Prevention's active, population-based, multiple-site ASD surveillance network for 8-year-olds since 2000. The 8-year-old methodology, designed to identify children both with and without prior diagnosis, was applied in SC with modification to include information sources for younger children.
  
  
  RESULTS
  The ASD prevalence among 4-year-olds in 2006 was 8.0 per 1000 (95% confidence interval [CI], 6.1-9.9), or 1 in 125. In comparison, ASD prevalence among 8-year-olds in the same geographic area was 7.6 (95% CI, 5.7-9.5) in 2000 and 7.0 (95% CI 5.1-8.9) in 2002. Developmental concerns were documented at earlier ages across time, and while most cases received services, only 20% to 29% received services specific to ASD.
  
  
  CONCLUSIONS
  Findings should provide useful information for the planning of health/education policies and early intervention strategies for ASD.
authors.affiliation: Department of Biostatistics, Bioinformatics, and Epidemiology, Medical University of South Carolina, Charleston, SC 29425-8350, USA. nicholjs@musc.edu
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Nicholas
authors.forename: Laura A
authors.initials: LA
authors.lastname: Carpenter
authors.forename: Lydia B
authors.initials: LB
authors.lastname: King
authors.forename: Walter
authors.initials: W
authors.lastname: Jenner
authors.forename: Jane M
authors.initials: JM
authors.lastname: Charles
mesh_terms: D001741:Black or African American; D017677:Age Distribution; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000453:epidemiology*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D013022:South Carolina / Q000453:epidemiology; D044465:White People