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Autism prevalence significantly higher, especially among boys
The prevalence of parent-reported autism spectrum disorders among children significantly increased from 2007, according to a report co-written by the CDC and the Health Resources and Services Administration. The increase of autism spectrum disorder diagnoses was greatest among boys and adolescents aged 14 to 17 years.
The increase continued through 2011-2012, the result of diagnoses of children with previously unrecognized ASD, according to the researchers.
The data for the report was collected by the CDC from the National Survey of Children’s Health, a nationally representative telephone survey of households with school-aged children.
Parent-reported ASD among children aged 6 to 17 years was 2% in 2011-2012 vs. 1.16% in 2007. Significant increases were observed for all age groups (1.31% to 1.82% for children aged 6 to 9 years; 1.45% to 2.39% for children aged 10 to 13 years; and 0.73% to 1.78% for adolescents aged 14 to 17 years).
The rise in ASD was especially pronounced among boys, increasing from 1.8% to 3.23%. The increase among girls was not statistically significant.
ASD diagnoses in 2008 or after accounted for the bulk of the increase in ASD prevalence, according to the researchers. For example, children diagnosed in 2008 or after represented 50% of those with a parent-reported ASD who were aged 6 to 9 years.
Children aged 6 to 17 years diagnosed in 2008 or after also were more likely to have a milder ASD than those diagnosed before 2007 (58.3% vs. 49.5%) and were less likely to have a severe ASD (6.9% vs. 16.9%).
“Together, these findings suggest that the increase in prevalence of parent-reported ASD may have resulted from improved ascertainment of ASD by doctors and other health care professionals in recent years, especially when the symptoms are mild,” the researchers wrote.
Perspective
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The prevalence of autism spectrum disorders continues to rise, according to the latest CDC National Health Statistics Report. Now the rate of parent-reported ASD among children aged 6 to 17 years is 2% in 2011-2012, with the greatest increase among boys aged 14 to 17 years, suggesting the change is due largely to increased recognition of milder conditions. The CDC used telephone surveys from parents in 2007 and 2011 to calculate the change in prevalence. Public awareness of autism has increased dramatically over the last 15 years, with many programs targeting parents and health professionals to recognize and treat children with autistic symptoms. The increase in the rates of autism may also reflect diagnostic practices. Forthcoming changes in DSM-5 seem to be aimed at curbing “diagnostic creep” and should increase the diagnostic specificity of autism by focusing on essential core element of social impairment. Studies such as this speak to the need for increased funding on the federal and state level to research, diagnose and treat this condition.
Perspective
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This rise in the prevalence of parent-reported autism spectrum disorder to 1 in 50 school-age children likely reflects both increases in identification of new cases in recent years as well as the broadening of the diagnosis. The greatest and most significant increases occurred in older children with milder cases rather than younger children. It is important to emphasize that these cases were defined by parent reports and not verified by professional sources, as in the Autism and Developmental Disabilities Monitoring Network, where rates currently are 1 in 88. Nevertheless, these findings reveal increased parent and professional awareness and identification of autism-related disabilities, particularly in older children with milder problems not previously identified with such special needs.