Autism rates jump, especially among children without co-occurring intellectual disability
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The estimated prevalence of autism among 8-year-olds in a New Jersey study more than tripled during a 6-year period, including a fivefold increase in children with autism who do not have a co-occurring intellectual disability.
In the study, two out of three children with autism did not have a co-occurring intellectual disability, according to Josephine Shenouda, DrPH, MS, an instructor at Rutgers School of Public Health and a research study manager at Rutgers New Jersey Medical School, and colleagues. Black children with autism were far less likely to be identified this way compared with white children, they found.
“We had the question of, do autism rates differ by intellectual disability?” Shenouda told Healio. “We knew that autism rates were increasing between 2000 and 2016, but we wanted to see if the rates were increasing equally between children that have autism plus an intellectual disability, and autism without intellectual disability.”
In a cross-section study, Shenouda and colleagues used data from the Autism and Developmental Disabilities Monitoring Network, a biannual surveillance tracking system that provides autism prevalence estimates for birth cohorts. They specifically used data from the years 2000 to 2016 in New Jersey’s Essex County, Hudson County, Ocean County and Union County, representing approximately a quarter of the state’s 8-year-old population.
In that time period, 4,661 children met the researchers’ case definition for autism, with the prevalence increasing more than threefold from 9.6/1,000 (95% CI, 8.5-10.7) in 2000 to 31.8/1,000 (95% CI, 30.0-33.8) in 2016. At the same time, the rate of autism with an intellectual disability increased more than twofold from 2.9/1,000 (95% CI, 3.6–5.0) to 7.3/1,000 (95% CI, 7.6–9.6), and autism without an intellectual disability increased nearly fivefold from 3.8/1,000 (95% CI, 3.3–4.7) to 18.9/1,000 (95% CI, 19.2–22.3).
“We knew we were identifying more children that did not have intellectual disability, but the rise was a bit surprising,” Shenouda said. “It was a steeper increase, and we didn't anticipate that.”
Also surprising, Shenouda said, was the “magnitude” of the socioeconomic and racial disparities in autism identification. Children with autism in affluent areas were 80% more likely to be identified without an intellectual disability compared with their peers in underserved areas, and Black children were 30% less likely to be identified this way compared with white children.
“It’s important to identify autism early, and the best tool we have in our toolbox is universal autism screening before 36 months,” Shenouda said. “It will identify children early, but it would also have the greatest benefit for children from underserved communities.”
In a related commentary, Emily Hotez, PhD, of the David Geffen School of Medicine at UCLA, and Lindsay Shea, DrPH, of the A.J. Drexel Autism Institute in Philadelphia, said population-level surveillance for autism is “critical for tracking and improving health equity for distinct demographic groups."
However, they argued that the findings in this study and other similar projects were “inherently limited by a lack of capacity to extrapolate findings beyond racial and ethnic group comparisons and link them to social determinants of health (SDOH), the underlying social, economic, and environmental conditions that lead to poor health outcomes and high health care costs.”
“In the long-term, wide-scale adoption of SDOH screening tools at the practice level will translate to autism researchers’ ability to analyze surveillance data to account for SDOH more thoroughly,” they wrote. “This will, in turn, inform regional and national efforts to combat health disparities for autistic populations. Autism surveillance researchers can model and build on existing efforts to assess SDOH.”
References:
Hotez E, et al. Pediatrics. 2023;doi: 10.1542/peds.2022-059541.
Shenouda J, et al. Pediatrics. 2023;doi:10.1542/peds.2022-056594.