"What is the prevalence of autism?
CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network released data in 2007 that found about 1 in 150 8-year-old children in multiple areas of the United States had an ASD.
Since the ADDM sites do not represent a nationally representative sample, the prevalence estimates should not be generalized to every community in the United States. Although accurate for the areas we studied, rates may be higher or lower in other areas. However, these prevalence estimates can help communities project how many children may have autism for planning and identification purposes. They can also be used to provide for more appropriate interventions for children with ASDs."
ADDM network results in the United States (bold added)
Results from CDC’s ADDM network showed the average ASD prevalence among states participating in the project was 6.7 per 1,000 children in 2000 (6 sites) and 6.6 per 1,000 in 2002 (14 sites), or approximately 1 in 150 children. Most sites identified between 5.2—7.6 per 1,000 8-year-old children with ASD in 2000 and 2002. There was some variation with ASD prevalence significantly lower in 1 site (3.3 in AL) and higher in 1 site (10.6 in NJ).
How many children in the United States have an ASD?
There is not a full population count of all individuals with an ASD in the United States. However, using the prevalence data stated above, we can estimate that if 4 million children are born in the United States every year and assuming the prevalence rate has been constant over the past two decades, we can estimate that up to 560,000 individuals between the ages of 0 to 21 have an ASD. However, many of these individuals may not be classified as having an ASD until school-age or later. Since behaviors related to the ASDs are usually present before the age of 3 years, it is important to make sure the individuals are being identified and are receiving appropriate intervention services as early as possible.
What is the difference between “incidence” and “prevalence”?
Incidence is the number of new cases of disease in a defined group of people over a specific time. Prevalence is the number of existing disease cases in a defined group of people during a specific time period. Public health professionals use prevalence measures to track a condition over time and to plan responses at local, regional, and national levels. Incidence is very difficult to establish because the exact time a person develops an ASD is not known.
