Autism Prevalence Up Sharply in Latest National Monitoring Report
Autism spectrum disorder is up 15 percent, on average, among communities monitored by the federal Centers for Disease Control and Prevention, the agency said Thursday.
Approximately 1 in 59 8-year-olds were diagnosed with the disorder, a prevalence number based on data collected in 2014 using a combination of medical and school records in 11 states. For the past two report cycles—2016 and 2014—1 in 68 8-year-olds were estimated to have the disorder, which is characterized by significant social, communication and behavioral impairments.
Within those numbers, though, is a large variation of autism prevalence among states. In New Jersey, 1 in 34 8-year-olds were identified as having an autism spectrum disorder, the highest rate of the states monitored. In contrast, 1 in 76 Arkansas children were identified with the disorder.
There were also wide disparities in prevalence by gender and by race. About 1 out of 38 of boys in these surveillance sites was diagnosed with autism, compared to 1 out of 152 girls. White children, with a prevalence rate of 1 in 58, were more likely to be diagnosed with autism spectrum disorder than black children (about 1 in 63) and Hispanic children (about 1 in 71).
The CDC says the surveillance numbers can't be extrapolated to the nation as a whole, because the monitoring sites are not a nationally representative sample. However, with the prevalence rate reaching 3 percent in some communities and with an overall increase of 150 percent since monitoring first started in 2000, autism spectrum disorder is an "urgent public health concern that could benefit from enhanced strategies to help identify ASD earlier; to determine possible risk factors; and to address the growing behavioral, educational, residential, and occupational needs of this population."
The sites monitored as part of the Autism and Developmental Disabilities Monitoring Network are in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin.
School Records Essential For Monitoring Autism Prevalence
School cooperation is essential in gathering these figures, as well as in identifying children and providing the services, said CDC scientists who worked on the report.
To gather data from schools, CDC researchers comb through the education and test records of children in the monitoring areas, said Daisy Christensen, a co-author of the new report and the surveillance team lead in the developmental disabilities branch of the CDC's National Center on Birth Defects and Developmental Disabilities. Rather than relying on district-level identification, evaluators rate student behaviors and test results to see if they meet the definitions of autism spectrum disorder.
"What we found is that we really are able to ascertain more children when we have access to education records," Christensen said. "Some children are not really identifed until they get to school."
The data also show that more children are being identified with autism who do not also have an intellectual disability. In previous reports, about half of the children identified also had an intellectual disability; in this report, the rate was around 30 percent.
The age at which children start to receive services has not changed in recent years, though there has been increasing importance put on early identification, said Stuart Shapira, the associate director for science in the National Center on Birth Defects and Developmental Disabilities. This report found that, as over the past several reports, children were identified at a median age of around 4.5 years.
But autism spectrum disorders can be diagnosed in some children as early as age 2. The percentage of children who received a comprehensive development evaluation by age 3 in this report, 42 percent, was also essentially unchanged from previous years.
"More work still needs to be done in that area," Shapira said. "The educators have a role to play, and physicians and parents have a role to play."
The surveillance data alone cannot explain what is driving the increase, the researchers said. But they did note that the prevalence rates among children of different races closed somewhat in this report. The prevalence differences among boys and girls also closed slightly. In previous years, boys were 4.5 times more likely to be diagnosed, but in this report, they were 4 times more likely.
The narrowing of those gaps may be driving some of the increase in prevalence rates, Christensen said.
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