Centers for Disease Control and Prevention (CDC) released 2020 data on the prevalence of autism in the United States. According to this, nearly one child in 36 8-year-olds has autism. The 2018 estimate was 1 in 44 children. This means that there has been a 20% increase since 2018. However, researchers say this reflects increased awareness and identification, not a rise in prevalence.
The latest estimate comes from the CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network. The unit compiled health and special education data for 226,339 children in 11 states.
The data shows that autism prevalence is 3.8 times in boys than in girls. This new estimate is narrower than the 2018 figure, which showed that autism was 4.2 times more prevalent in boys. In girls, the prevalence is 1 in 88. This is the highest recorded figure.
The new data has also traversed the barrier of race. The persisting racial inconsistencies when identifying autism were eliminated. This means that children from Hispanic, Black, Asian or Pacific Island backgrounds had a higher prevalence of autism than white children. This was recorded for the first time.
While this has been a breakthrough, some gaps remain. For example, black children with comorbid autism and intellectual disability were identified. Their numbers were significantly higher than children from other racial groups. This suggested that Black children without intellectual disabilities fell through the cracks.
Another important discovery was the increase in autism prevalence in 4-year-olds. This was covered in a companion report. In 4-year-olds, prevalence increased by 26 per cent compared to the 2018 data. In 2018, 1 child in 59 had autism; in 2020, the ratio was 1 in 47. ADDM recorded data for 227,526 children across the same 11 US states.
There was a similarity with the 8-year-old group. Children from Hispanic, Black, Asian or Pacific Island were identified at higher rates than white children. For girls aged 4, autism prevalence was 1 in 96. In 2018, the figure was 1 in 130. For the first time in ADDM history, the figure has surpassed 1 in 100.
Epidemiologist Matthew Maenner works for CDC’s National Center on Birth Defects and Developmental Disabilities. He led the report on autism prevalence in 8-year-olds. Maenner noted that the prevalence for girls is now similar to that for boys in 2002.
“You could wonder if in the future we might start saying that that ratio might be changing.” ~ Matthew Maenner
Katharine Zuckerman, associate professor of pediatrics at Oregon Health & Science University in Portland, says, “We may see another little prevalence bump in the next ADDM report as all the kids who weren’t assessed during the pandemic finally get assessed.” Zuckerman was not associated with the CDC report.
Kelly Shaw, an epidemiologist with the National Center on Birth Defects and Developmental Disabilities, who led the report on 4-year-olds, added that by age 8, most children are already diagnosed in health and school records. Therefore, by this age, fewer new identifications are being recorded.
Both epidemiologists and their teams have begun estimating the prevalence of autism for 2022. This data will allow the researchers to have more data points to study these patterns.
Both estimates show that the identification for autism increased for children who showed signs of autism but did not have access to care until they were older. But there is a disparity among those with access to timely, high-quality and evidence-based services. Specifically for children from diverse racial backgrounds, identification is not enough if they do not receive high-quality services.
Researchers are unsure when the increase in autism prevalence in the U.S. will level out. They agree on the fact that forecasting a trend is difficult. Over ten years ago, multiple locations had a consistent autism prevalence (1 child in 100). Researchers, like Maennerthought that this data was close to the real number of children with autism. It was nowhere near the ceiling.
The COVID-19 pandemic left its mark on these findings. In six months leading up to March 2020, 4-year-old children were evaluated and identified at higher rates than in 2016. But when the pandemic hit, this trend reversed. By the end of 2020, there was an uptick in evaluation and identification, but it wasn’t at the same level as the pre-pandemic times.
The pandemic hindered in-Person data collection. A possible result was 8-year-olds being undercounted in some locations. But the effects of the COVID-19 pandemic on children are unclear.
Zuckerman thinks that the findings can be generalised to other countries as well to an extent. “This is a good sign that the pretty significant efforts that pediatricians and public health people and communities are doing towards improving awareness, reducing stigma, improving screening and referring at-risk kids to services”, she adds.
A 2022 study estimates that globally, 1 in 100 children have autism. Their estimate is an average of data recorded across various studies. Several well-controlled studies have reported significantly higher figures. However, for many low and middle-income countries, data is unknown.
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