Changes in autism spectrum disorder prevalence in 4 areas of the United States.
BACKGROUND
We sought to describe autism spectrum disorder (ASD) population characteristics and changes in identified prevalence across 3 time periods.


METHODS
Children with a potential ASD were identified through records abstraction at multiple sources with clinician review based on Diagnostic and Statistical Manual (DSM-IV-TR) criteria. Multisite, population-based data from the Autism and Developmental Disabilities Monitoring (ADDM) Network were analyzed from areas of Arizona (AZ), Georgia (GA), Maryland (MD), and South Carolina (SC). Participants were 8-year-old children (born in 1992, 1994, or 1996) in 2000, 2002, or 2004 (and children born in 1988 residing in metropolitan Atlanta in 1996) who had been evaluated for a variety of developmental concerns at education and/or health sources.


RESULTS
From 2000 to 2004, the identified prevalence of the ASDs per 1,000 8-year-old children showed significant increases of 38% in GA and 72% in MD and a nonsignificant increase of 26% in AZ. ASD prevalence was relatively stable in SC with a nonsignificant decrease of 17%. Males had a higher identified prevalence of ASD in all years. Increases among racial, ethnic, and cognitive functioning subgroups varied by site and surveillance year. More children were classified with an ASD by community professionals over time, except in AZ.


CONCLUSIONS
There was a trend toward increase in identified ASD prevalence among 8-year-old children who met the surveillance case definition in 3 of the 4 study sites from 2000 to 2004. Some of the observed increases are due to improved ascertainment; however, a true increase in ASD symptoms cannot be ruled out. These data confirm that the prevalence of ASDs is undergoing significant change in some areas of the United States and that ASDs continue to be of urgent public health concern.
National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. crice@cdc.gov
Catherine
C
Rice
Joyce
J
Nicholas
Jon
J
Baio
Sydney
S
Pettygrove
Li-Ching
LC
Lee
Kim
K
Van Naarden Braun
Nancy
N
Doernberg
Chris
C
Cunniff
Craig
C
Newschaffer
F John
FJ
Meaney
Jane
J
Charles
Anita
A
Washington
Lydia
L
King
Maria
M
Kolotos
Kristen
K
Mancilla
Cynthia A
CA
Mervis
Laura
L
Carpenter
Marshalyn
M
Yeargin-Allsopp
D001213:Asian / Q000706:statistics & numerical data; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis / Q000453:epidemiology*; D003071:Cognition; D002658:Developmental Disabilities / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008403:Mass Screening; D011159:Population Surveillance; D015995:Prevalence; D011594:Psychometrics; D014481:United States / Q000453:epidemiology