The prevalence of autism spectrum disorder among school-age children rose from about 1.2% to 2% over the last 5 years, the Centers for Disease Control and Prevention has reported.
Reports from parents revealed that among children aged 6-17 years, a diagnosis of autism spectrum disorder (ASD) occurred in about 1 in 86 children in 2007. By 2011-2012, parents reported ASD diagnoses for 1 in 50 children in that age group. The results are based on new data from the 2011-2012 National Survey of Children’s Health.
But the increase in prevalence is likely because of an increased awareness of ASD and better diagnosis by physicians, the CDC researchers wrote, rather than a "true" increase. The researchers reached that conclusion in part based on the number of new diagnoses occurring in older children.
"Changes in the ascertainment of ASD could occur because of changes in ASD awareness among parents or health care professionals, increased access to diagnostic services, changes in how screening tests or diagnostic criteria are used, or increased special education placements in the community," they wrote.
The researchers found statistically significant increases in the prevalence of ASD for all age groups and for boys. There was a small increase in ASD prevalence among girls, but it was not statistically significant. During 2011-2012, boys were more than four times as likely as girls aged 6-17 years to have a diagnosis of ASD.
The analysis also examined the severity of ASD diagnoses. Children who were diagnosed in 2008 or later were less likely to have a severe form of ASD. Only about 7% of the new diagnoses were for severe ASD, compared to nearly 17% for children diagnosed in 2007 or earlier.