In addition to sex differences, the report found wide variations in prevalence estimates by sites, and by racial and ethnic groups. For example, the prevalence of ASDs ranged from 1 of every 210 children in Alabama to 1 of every 47 children in Utah. And at all the sites, the estimated prevalence in non-Hispanic white children was significantly higher than the prevalence in non-Hispanic black children and Hispanic children overall, with one exception: In Florida, the prevalence was significantly higher in Hispanic children than in non-Hispanic white or non-Hispanic black children.
The estimated prevalence of ASD was also significantly higher at sites where there was access to education sources, compared with the sites that only had health sources to help identify cases.
In 2008, the 14 sites covered an area that included a total of about 337,000 children aged 8 years, representing about 8% of the 8-year-olds in the United States. Although the report notes that the ADDM sites are not nationally representative and the results should not be generalized to the United States overall, Dr. Boyle said these trends are comparable to the prevalence estimates in other national surveys.
The ADDM sites are in Alabama, Arizona, Arkansas, Colorado, Florida, Maryland, Missouri, New Jersey, North Carolina, Pennsylvania, South Carolina, Utah, West Virginia, and Wisconsin.
No conflicts of interest were reported.
More information about autism, including a link to the report, is available from the CDC.
* Updated: Additional information added April 4, 2012