Roughly 1 in 30 — 3.49% — of children and adolescents ages 3 to 17 were diagnosed with an autism spectrum disorder (ASD) in 2020, according to a JAMA Pediatrics research letter published this month by a team of researchers in China.
The letter also referenced a new study showing a 53% increase in ASD in American young people since 2017.
The researchers used data, gathered in 2019 and 2020, from the U.S. National Health Interview Survey (NHIS), which collects health-related information via household interviews conducted by the U.S. Census Bureau.
During the NHIS interviews, a parent or guardian reported on ASD diagnoses made by a physician or other healthcare professional.
Of the 12,554 individuals ages 3 to 17 surveyed in 2019 and 2020, 410 were reported to have a diagnosis of ASD.
The research team, including corresponding author Dr. Wenhan Yang, M.D., Ph.D., from the School of Public Health, Guangdong Pharmaceutical University in China, compared the 2019 and 2020 NHIS results to NHIS results from the years 2014 to 2018.
“We found the prevalence of ASD increased from 2014 to 2016, decreased from 2016 to 2017, and then increased again from 2017 to 2020,” Yang and colleagues wrote.
The study showed an ASD diagnosis rate of 2.79% in 2019 and 3.39% in 2020 — which is a 53% increase since 2017 — and reported an overall ASD diagnosis rate of 3.14% in 2019 and 2020.
The researchers said the 2019 and 2020 prevalence rates were higher than those reported in other countries and geographical areas since 2014 — including Europe (0.42% to 3.13%), the Middle East (0.11% to 1.53%) and Australia (1.41% to 2.52%).
The data showed a higher prevalence of ASD in boys. For 2019 and 2020, 4.64% of boys were reported as having been diagnosed with ASD versus 1.56% of girls.
The study authors also found a statistically significant higher rate of ASD diagnosis among lower-income demographics.
The authors noted a limitation of their research is that it relied on parents’ recall of information, which may biased or incomplete.
Brian Hooker, PhD., P.E., said the researchers’ findings are important because their data capture ASD diagnosis information that other measurements of ASD diagnosis rates may have missed.
Hooker, chief science advisor at Children’s Health Defense, said every four years the Centers for Disease Control and Prevention (CDC) publishes an update on its estimate of the rate of autism in children, through the agency’s Autism and Developmental Disabilities Monitoring (ADDM) Network.
The ADDM data, however, tends to underestimate the rate of autism, according to Hooker, because it draws largely from reports of higher-income families and looks only at diagnosis rates of 8-year-olds.
The NHIS data used by Yang and colleagues “are more accurate and more reflective of where cases are missing in the CDC’s numbers because people in the ADDM Network tend to be of a higher-income demographic,” he said. “This study has really captured the lower end of poverty-level income demographics.”