Autism Prevalence Higher Than Previously Reported in Communities Across the U.S.

Autism is being diagnosed at a higher rate and at younger ages in the United States, according to a new report released by the Centers for Disease Control and Prevention (CDC). Using 2018 data from 11 communities, investigators found that the prevalence of autism diagnosis has risen to 1 in 44 children, compared with 1 in 54 children in 2016.

A second report, on 4-year-old children in the same 11 communities, showed gains in diagnosing autism at an earlier age. This group of children were 50 percent more likely to receive an autism diagnosis or special education classification by 48 months of age compared with children born in 2010 (8-year-olds). Both reports were published in the CDC’s Morbidity and Mortality Weekly Report.

“The substantial progress in early identification is good news, because the earlier that children are identified with autism, the sooner they can be connected to services and support,” said Karen Remley, MD, the director of the CDC’s National Center on Birth Defects and Developmental Disabilities, in a CDC press release. “Accessing these services at younger ages can help children do better in school and have a better quality of life.”

Nationwide Autism Surveillance Conducted Every 2 Years

This report comes from a CDC-sponsored nationwide autism surveillance program called the ADDM (Autism and Developmental Disabilities Monitoring Network) that has been reporting for about 20 years, says Kurt Klinepeter, MD, a professor of developmental pediatrics at Atrium Health Wake Forest Baptist in Winston-Salem, North Carolina.

“This surveillance is done every two years, and these prevalence and demographic data are published in the MMWR, usually about three years later. So, the current 2021 report is for the 2018 surveillance year. The sites are a mix of urban and rural, geographically diverse, so that a cross section of autism prevalence is reported,” he says.

Other participating communities were in Arizona, Arkansas, California, Georgia, Maryland, Minnesota, Missouri, New Jersey, Tennessee, and Wisconsin. Although these sites are scattered throughout the country, the findings are a snapshot of ASD in these communities and not a national estimate of autism prevalence in the United States, according to the authors of the report.

Autism Identification Rates Can Be Twice as High in Some Communities

The prevalence of autism in the communities studied ranged from 1 in 60 children (1.7 percent) in Missouri to 1 in 26 children (3.9 percent) in California. According to the researchers, these variations could be due to how communities identify children with autism and the level of services for children with autism and their families.

Although there is variability in prevalence from community to community, the sites that report have been more or less consistent over time, so a review of the data trends for a specific site is enlightening, says Dr. Klinepeter.

For example, at the ADDM community site in Utah, which covers Salt Lake City and surrounding counties, the prevalence of autism among 8-year-old Utah children has risen by nearly 30 percent in less than a decade.

University of Utah Health scientists attribute much of that rise to a heightened awareness of autism, better diagnostic tools to detect it, and improved access to medical care, according to a University of Utah Health press release.

Racial and Ethnic Differences in Identifying Autism Persist

In several of the 11 communities the report described, including Utah, fewer Hispanic children were identified with autism than Black or white children.

This finding suggests that disparities in getting an ASD diagnosis due to ethnicity could be a problem, said Amanda Bakian, PhD, a coauthor of the study, an associate professor of psychiatry at the Huntsman Mental Health Institute at the University of Utah, and a principal investigator of the Utah ADDM study, in the release.

Authors of the study also found that a higher percentage of Black children with autism were identified with intellectual disability compared with white or Hispanic children with autism.

Report Highlights a Need for More Diagnostic and Treatment Services

When interpreting these findings, it’s important to keep in mind how the information on autism diagnosis is gathered for this report, says Klinepeter. “The diagnoses of 8-year-olds in these surveillance regions is based on a paperwork review (school, medical, and other records), although not every site has access to all types of records,” he says.

That’s important, because it means that some of the autism diagnoses were made on these 8-year-old children without a face-to-face assessment, says Klinepeter. “Essentially, when autism is mentioned in the records, the diagnosis is not verified. It may have been made based on a comprehensive diagnostic assessment, but it also may be stated in passing without the benefit of a comprehensive assessment,” he says.

If the prevalence of autism is truly increasing, increased awareness and referral for assessment and services can account for some of this, Klinepeter says. “Certainly, the need for more diagnostic and treatment services for this population is imperative,” he says.

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