U.S. autism prevalence inches upward as racial gaps shut | Spectrum
Improving Identification: Rising autism prevalence numbers are more likely to be due to improved identification and diagnosis than a real change in prevalence, experts say.
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The autism prevalence in the United States rose to 1 in 44 children in 2018, up from 1 in 54 in 2016, according to a new study examining autism prevalence in 8-year-olds in 11 states. As in previous years, the increase is likely due to improvements in identification, diagnosis, and routing to services rather than an increase in the number of children with autism, experts say.
The US Centers for Disease Control and Prevention (CDC) released the report today.
The data is based on health and educational records of 220,281 children collected through the CDC Network for Autism and Developmental Disability Monitoring (ADDM). States on the ADDM network include Arizona, Arkansas, California, Georgia, Maryland, Minnesota, Missouri, New Jersey, Tennessee, Utah, and Wisconsin.
About 4.2 times as many boys as girls have been identified with autism, a gender ratio that is consistent with previous ADDM reports and other prevalence estimates.
Among children who were 4 years old in 2018, the prevalence of autism was 1 in 59, according to an accompanying report of 220,394 children at the 11 ADDM locations. This number has increased to 1 in 64 children compared to the 2016 estimate. When compared to the older cohort, these children were about 1.5 times more likely to either be diagnosed with autism or in need of special education by the age of 4, the study found.
“Part of this change certainly seems to be due to the way children are identified, diagnosed, and cared for in their communities,” said Matthew Maenner, epidemiologist and director of the CDC’s National Center on Birth Defects and Developmental Disabilities monitoring team, who led the report over 8 year olds.
“What is really revealing is the local practice and the variability in local practice, and our continued need to address problems related to systemic health inequalities,” said David Mandell, professor of psychiatry at the University of Pennsylvania in Philadelphia, on none of the reports. “But I think we need to stop looking at it as an accurate estimate of the prevalence of autism in the United States.”
As in the 2016 surveillance year, there were no significant differences in autism prevalence among white, black, Asian, or Pacific islanders, suggesting that early screening and identification helped reduce racial differences in the early detection of autism.
On average, the prevalence numbers of Hispanic children were comparable to those of other groups, but in 5 of the 11 ADDM locations, Hispanic children were identified less often than their white, black, Asian, or Pacific islanders, Maenner says.
“That was hard to communicate this year,” he says. “It looks like things come to an end with the 8-year-old every year.”
However, the situation is different for children who were 4 years old in 2018. The latest ADDM report on 4 year olds includes children from all 11 locations, while the report for 2016 only included 6 locations. Based on a larger body of data, the ADDM investigators found that the prevalence was lowest among white children compared to black, Hispanic, Asian, and Pacific islanders.
That difference isn’t because one location is driving the average up, but rather by a broader trend across all 11 locations, says Kelly Shaw, epidemiologist at the National Center on Birth Defects and Developmental Disabilities, who led the 4-year-old report . “Hopefully it reflects better access to services,” she says.
In agreement with the reports from previous years, a disproportionately high number of autistic black children in both age groups was identified with an intellectual disability. One possible explanation is that health care providers may not become aware of children without intellectual disabilities as quickly, says Stuart Shapira, assistant director of science at the National Center on Birth Defects and Developmental Disabilities, who was not involved in the new reports.
This problem can be more pronounced in black children due to systemic prejudice. “If vendors see a black kid and they’re linguistically lagging and their social communication is poor, do it [the providers] do you think about autism Or do you just think this child has an intellectual disability or a behavior problem? ”Asks Katherine Zuckerman, Associate Professor of Pediatrics at Oregon Health and Science University in Portland, who was not involved in the new studies.
ADDM reports usually appear every two years in March. The previous one was released in March 2020. This year’s reports came a few months earlier than usual, thanks to new methods of estimating prevalence at the 11 ADDM sites, the researchers say.
Rather than having ADDM clinics examine data from school records and individual children’s medical records – a time-consuming and data-intensive process that has been used in recent years – the new method relies on records of autism diagnoses from clinicians, special educational classifications of autism and Hospitals billing codes for autism services that produce similar results with half the data.
In the midst of the coronavirus pandemic, the new approach enabled investigators at the ADDM locations to complete their work with minimal data access problems, says Maenner.
But the new methods might not address some of the inadequacies of the ADDM data, says Mandell. “They base their accounts solely on what is in the medical record, and [researchers at different sites] have variable access to these data sets ”, which could explain part of the regional variability.
Mandell says he would like to see resources go beyond just tracking prevalence into service and support systems for autistic children and their families.
“How do we feel about improving the quality and inclusiveness of educational care, the ability of general practitioners and specialist practitioners to provide adequate care to address rather than perpetuate the many causes of disability and suffering these children and their families experience? Invest resources in counting? ”He says.
To this end, investigators from the ADDM network are collecting data on 16-year-olds with autism, tracking problems related to their mental health, concurrent illnesses and problems transitioning into adulthood, says Maenner.
With reporting by Angie Voyles Askham.