A 2019 study showed that this disproportionately affected Black and Hispanic children, who had significantly less access to health care professionals than White children.
As a result, “the old methodology had a bias built into it,” Maureen Durkin, PhD, DrPH, coauthor of that study and chair of population health sciences at the University of Wisconsin–Madison and principal investigator for the ADDM site in Wisconsin, told this news organization.
“Clinician reviewers ended up putting these children in the ‘suspected ASD’ category because they couldn’t call it a case under the case definition,” Dr. Durkin said. “There was a fairly large percentage of suspected cases and a disproportionate number of those kids were children of color.”
Although she can’t say for sure, Dr. Durkin said it’s possible the new protocol could eliminate some of that bias.
CDC researchers also attribute the new method to an expanded study of early diagnosis among 4-year-olds. In previous years, only a handful of the ADDM Network sites participating in the 8-year-old surveillance project also studied early diagnosis in 4-year-olds.
This year, all 11 sites took part in the early diagnosis analysis, tripling the number of children included in the analysis. That made it possible to include, for the first time, Asian/Pacific Islander children in this analysis.
In the past, ASD prevalence has trended higher in White children, compared with other racial groups. The new data found that ASD prevalence among 4-year-olds was significantly lower in White children (12.9 per 1,000 children) than in Black, Hispanic, or Asian/Pacific Islander children (16.6, 21.1, and 22.7 per 1,000, respectively). Prevalence in American Indian/Alaska Native children was the lowest among all racial groups (11.5 per 1,000).
It’s the first time researchers have seen this pattern in any ADDM report, Kelly Shaw, PhD, lead author of that study and an epidemiologist with the National Center on Birth Defects and Developmental Disability at the CDC, told this news organization.
These data don’t provide clues about the potential cause of that disparity, Dr. Shaw said. It’s likely an indication of better identification of ASD in those communities, she said, and not a sign of increased incidence of autism among Black, Hispanic, or Asian/Pacific Islander children.
“We don’t have any evidence to suggest or expect that autism would be increasing differentially among groups,” Dr. Shaw said.
The data suggest “we are making some progress but there certainly is still room for improvement,” Dr. Shaw said.
Study authors report no conflicts of interest.
A version of this article first appeared on Medscape.com.