Posted on the Pediatric SuperSite on October 28, 2009
Researchers attributed highest autism rates yet to better detection
Among U.S. children, 110 of every 10,000 have autism,
new estimates from a nationally representative study indicated — a sharp
increase from the two to five per 10,000 reported from the 1960s to the 1980s
and the 30 to 60 per 10,000 reported in the earlier part of this decade.
“Methodologic changes between the surveys (with the
inclusion of Asperger’s disorder, pervasive developmental disorder and
other autism spectrum disorders [ASD]) and overall increases in public
awareness and provider identification of ASD might partly explain the increased
prevalence,” wrote researchers from the Department of Health and Human
Services and Harvard Medical School.
Younger average age at diagnosis, more widely available
diagnostic services, greater public awareness and growing acceptance of autism
as a co-condition with other developmental disorders were among additional
factors the researchers said may help explain the increases in prevalence.
Calculations were based on data from the 2007 National
Survey of Children’s Health, a random digit–dial telephone survey
involving information from 78,037 children aged 3 to 17 years. Using weighted
point-prevalence models based on parent-reported data, the researchers
estimated that 673,000 U.S. children currently have ASD.
ASD in the sample population was most often described as
mild (49.6%), followed by moderate (33.9%) and severe (16.5%). Parental
education was the only significant predictor of severity; parents with less
than 12 years of education were more likely to rate their child’s autism
as moderate or severe (68%) compared with parents who had more education
(43.5%).
Findings also confirmed previously reported trends
including four times greater odds for ASD among boys compared with girls and a
higher likelihood of ASD diagnosis among non-Hispanic white children compared
with non-Hispanic black and multiracial children.
Researchers also determined that 40% of children whose
parents reported that their child received a previous ASD diagnosis did not
currently have the disorder. Possible explanations for the discrepancy included
initial misdiagnosis on the basis of mental retardation or another learning
disability and suspected ASD that was later ruled out.
Because parent-reported ASD was never confirmed by
external sources, another possibility is that some parents with children who
meet current criteria for the disorder may have responded “no”
because their child did not receive special services, according to the
researchers.
“This may be driven by the unique circumstances of
ASD, which require treatment and coordination among an unusually large number
of health and other disciplines, including primary care, educational,
rehabilitation and behavioral health services,” the researchers wrote.
“Further understanding of the groups at highest
risk for being diagnosed with ASD and the factors associated with current ASD
symptoms, severity and health care impact could lead to more effective
interventions.”
Kogan MD. Pediatrics. 2009;124:1-9.
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