US autism rates have increased nearly 10% over a 4-year period, new research from the Centers for Disease Control and Prevention (CDC), show.
However, this increase is likely because of continued progress in early screening and diagnosis, and improved detection in minority groups, the CDC said today.
The latest estimates show that 1 in 54 children (18.4 per 1000) aged 8 years was diagnosed with autism spectrum disorder (ASD) in 2016, up from 1 in 59 children (16.8 per 1000) in 2014, and 1 in 68 (14.6 per 1000) in 2012, as previously reported by Medscape Medical News.
The latest estimates appear in the March 27 issue of Morbidity and Mortality Weekly Report.
Fewer Racial Differences
The data stem from the CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network, a tracking system that provides estimates of the prevalence and characteristics of ASD among 8-year-old children in 11 communities in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin.
For the first time, rates of ASD were the same for black and white children (18.5 and 18.3 per 1000, respectively), but lower for Hispanic children (15.4 per 1000), suggesting a need to expand screening and intervention among this group.
Black and Hispanic children with ASD were also less likely to have a first evaluation by age 36 months than white children with ASD.
Overall, however, more children are being evaluated for and diagnosed with ASD at an earlier age, according to the latest data from the Early Autism and Developmental Disabilities Monitoring (Early ADDM) Network, reported separately in MMWR.
The Early ADDM data show that 74% of 4-year-old children with autism in 2014 received a developmental evaluation by age 36 months. This increased to 84% of 4-year-old children with autism in 2016. In addition, more children who were born in 2012 received an ASD diagnosis by 4 years of age compared with children born in 2008.
The latest data also continue to show that boys are about four times as likely to be diagnosed with ASD as girls, in-line with previous reports.
Among the 10 ADDM sites with sufficient data on intellectual ability, 33% of children with ASD were classified as having an intellectual disability (IQ ≤ 70).
This percentage was higher among girls than boys (40% vs 32%) and among black and Hispanic than white children (47%, 36%, and 27%, respectively). In addition, 24% had an IQ in the borderline range (IQ 71-85), and 42% had IQ scores in the average to above-average range (IQ > 85).
Overall ASD prevalence continues to vary widely among the 11 ADDM communities, ranging from a low of 1 in 76 in Colorado to a high of 1 in 32 in New Jersey. This may be because of how autism is diagnosed and documented in different communities, the CDC said.
“The new report demonstrates real progress in early screening and diagnosis,” Pamela Dixon, PhD, clinical psychologist director at Autism Speaks, told Medscape Medical News.
However, “black and Hispanic children identified with autism received evaluations at older ages than similar white children, again indicating that more needs to be done in this area,” said Dixon.
“Core to our mission since our founding has been to increase screening and lowering the age of diagnosis, especially in minority populations. The closing of the diagnosis gap among black, Hispanic, and white children is a testament to the work of thousands of Autism Speaks advocates and volunteers and community partners, as well as campaign partners Ad Council and BBDO whose award-winning work made this possible. It shows that when nonprofits make an issue a priority, change happens,” said Dixon.
“As the prevalence of autism continues to rise, we are as steadfast as ever in our work to achieve our vision: that all people with autism can reach their full potential,” Dixon added.
The CDC’s latest ASD estimates were released in advance of World Autism Month in April and World Autism Awareness Day on April 2.
MMWR Surveill Summ. 2020;69:1-12. Full text