Results from Arizona's First Population-Based Autism Study: UA Researchers Find
Autism Prevalence in Maricopa County Similar to Rates in Other U.S Regions

"This is the first population-based study conducted in Arizona on autism spectrum disorders," said Steele Center co-principal investigator Christopher Cunniff, MD, professor of pediatrics at The University of Arizona College of Medicine.

"We found that our prevalence is similar to most of the other states involved in the study," he said. "The prevalence in Maricopa County did not differ between the two study years. Almost all the children we identified are receiving special education services," says co-principal investigator John Meaney, PhD, research associate professor of pediatrics.

Sydney Pettygrove, PhD, assistant professor with the UA Mel and Enid Zuckerman College of Public Health, also was involved in the study. "Autism is a serious condition affecting many children and their families," she said. "The results of studies such as these provide information that will help us better understand when and how children with autism are being diagnosed and treated."

The results showed an average of 6.7 children out of 1,000 had an ASD in the six communities assessed in 2000, and an average of 6.6 children out of 1,000 having an ASD in the 14 communities included in the 2002 study. This means that approximately one in 150 children was found to have an ASD. All children in the studies were 8 years old because previous research has shown that most children with an ASD have been identified by this age.

Arizona ASD Prevalence Highlights:

Total 8-year-old children in the study area

2000:

45,322 8-year-old children (57.7 percent of all 8-year-olds in Arizona) 54.2 percent White, non-Hispanic 4.5 percent Black, non-Hispanic 41.3 percent Other race/ethnicity 10.7 percent of children in special education

2002:

45,113 8-year-old children (55.2 percent of all 8-year-olds in Arizona) 56.0 percent White, non-Hispanic 5.30 percent Black, non-Hispanic 34.0 percent Other race/ethnicity 13.9 percent of children in special education

Arizona ASD Prevalence:

Study Year 2000 -

Number of 8-year-old children identified with an ASD = 295 Total prevalence of ASDs: 6.5 per 1,000 Three boys to every girl with ASD: Boys: 9.7 per 1,000 Girls: 3.2 per 1,000 White, non-Hispanic: 8.6 per 1,000 Black, non-Hispanic: 7.3 per 1,000 Age of ASD Diagnosis 4 years, 5 months (median) 97 percent of children identified with an ASD were receiving special education services 32 percent of those receiving special education services had an autism eligibility

Study Year 2002 -

Number of 8-year-old children identified with an ASD = 280 Total prevalence of ASDs: 6.2 per 1,000 Boys: 10.1 per 1,000 Girls: 2.2 per 1,000 White, non-Hispanic: 7.7 per 1,000 Black, non-Hispanic: 6.3 per 1,000 Hispanic: 3.4 per 1,000 Age of ASD Diagnosis 5 years, 3 months (median) 97 percent of children identified with an ASD were receiving special education services 40 percent of those receiving special education services had autism eligibility

For decades, the best estimates for the prevalence of autism were four to five per 10,000 children. More recent studies summarized from multiple countries conducted with different methods, but using the most current diagnostic criteria, found a range of ASD prevalence between one in 500 children and one in 166 children.

Overall, the 2000 study found ASD rates ranged from one in 222 children to one in 101 8-year-old children in the six communities studied, while the 2002 study found ASD rates ranging from one in 303 to one in 94 among 8-year-old children. The average finding of 6.6 and 6.7 per 1,000 8-year-olds translates to approximately one in 150 children in these communities. This is consistent with the upper end of prevalence estimates from previously published studies, with some of the communities having an estimate higher than those previously reported.

"Autism is a serious public health problem which impacts too many children and their families," said CDC Director Julie Gerberding, MD, MPH. "The data we are presenting today will help us better understand the extent of this problem and enable us to continue to focus on promising areas of research in hopes that our children can grow and lead the happiest and most productive life possible."

Marshalyn Yeargin-Allsopp, MD, chief of CDC's autism program, said it is extremely difficult to accurately estimate the number of children who have autism or an autism spectrum disorder. Medical records often do not provide such information, and identification is made often only by schools or education specialists. The data reported today by the Autism and Development Disabilities Monitoring (ADDM) Network was designed to provide more consistent and reliable estimates.

"CDC has been working diligently to get an accurate understanding of the number of children affected by autism," she said. "We share the ADDM Network partners' commitment in documenting the prevalence of autism."

The purpose of CDC's autism spectrum disorder project was to develop a system for better understanding the size and characteristics of the population of children with an ASD. In addition to trying to measure the number of children with an ASD, the studies also looked at when parents and others first noted signs of developmental concern in their children. The 2000 and 2002 studies found 51 percent to 91 percent of children with ASDs had documented developmental concerns before age 3. Half of the children were diagnosed with an ASD between when they were between 4-and-half and 5-and-half years old. The most commonly documented concerns were in language development, followed by social concerns.

While these studies did not investigate the causes of ASDs, CDC's Centers for Autism and Development Disabilities Research and Epidemiology (CADDRE) Network also is doing a multi-state study to help identify factors that may put children at risk for autism spectrum disorders and other developmental disabilities.

The Autism and Developmental Disabilities Monitoring (ADDM) Network Studies:
An Overview

The data reported today by the ADDM network provides more specific information collected in many different communities in the United States using the same study methods.

The 2000 study included approximately 4.5 percent of U.S. 8-year-old children (children born in 1992), with the children from six states: Arizona, Georgia, Maryland, New Jersey, South Carolina and West Virginia. A total of 1,252 8-year-olds were identified as having an ASD.

The 2002 study included approximately 10 percent of U.S. 8-year-old children (children born in 1994), with the children from 14 states: Alabama, Arizona, Arkansas, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, Pennsylvania, South Carolina, Utah, West Virginia and Wisconsin. A total of 2,685 8-year-olds were identified as having an ASD.

This project is being conducted by CDC, University of Alabama at Birmingham, The University of Arizona, University of Arkansas, Colorado Department of Public Health and Environment, Johns Hopkins University, Washington University in St. Louis, University of North Carolina at Chapel Hill, University of Medicine and Dentistry of New Jersey in Newark, University of Pennsylvania School of Nursing, Medical University of South Carolina, University of Utah, Marshall University and the University of Wisconsin-Madison. Six sites participated in the 2000 project, and an additional eight were added for the 2002 project.

ASDs are developmental disabilities and are defined by considerable impairments in social interaction and communication and the presence of unusual behaviors and interests. They can be diagnosed as early as 18 months and last throughout a person's life.