Researchers at the Johns Hopkins Bloomberg School of Public Health contributed to a new U.S. Centers for Disease Control and Prevention (CDC) report that finds the prevalence of autism spectrum disorder (ASD) largely unchanged from two years ago, at one in 68 children (or 1.46 percent). Boys were 4.5 times more likely to be identified with ASD than girls, an established trend. The rate is one in 42 among boys and one in 189 among girls.

ASD is a developmental disorder characterized by social and communication impairments, limited interest and repetitive behaviors. Early diagnosis and intervention are important to improving learning and skills. Rates have been rising since the 1960s, but researchers do not know how much of this rise is due to more children being diagnosed with ASD or if actual cases are increasing or a combination of both. The CDC's first prevalance report, which was released in 2007 and was based on 2000 and 2002 data, found that one in 150 children had ASD.

For this new report, the CDC collected data at 11 regional monitoring sites that are part of the Autism and Developmental Disabilities Monitoring (ADDM) Network in the following states: Arkansas, Arizona, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, South Carolina, Utah, and Wisconsin. The Maryland monitoring site is based at the Johns Hopkins Bloomberg School of Public Health.

"Although we did not observe a significant increase in the overall prevalence rates in the monitoring sites, we continue to see the disparity among racial and ethnic groups," says Dr. Li-Ching Lee, PhD, ScM, a psychiatric epidemiologist with the Bloomberg School's departments of Epidemiology and Mental Health, and the principal investigator for the Maryland-ADDM. "For example, in Maryland, we found that Hispanic children were less likely to be evaluated for developmental concerns and therefore less likely to be identified."

In Maryland, Lee notes, the vast majority of children (95 percent) identified with ASD had a developmental concern in their records by age three, but only 55 percent of them received a comprehensive evaluation by age three. "This lag may delay the timing for children with ASD to get diagnosed and receive needed services," Lee says.

The prevalence in Maryland was one in 55 children (1.82 percent) with one in 34 among boys and one in 161 among girls. The data were derived from health and special education records of children who were eight years old and living in Baltimore County in 2012.

This is the sixth report by the CDC's Autism and Developmental Disabilities Monitoring Network (ADDM), which has used the same surveillance methods for more than a decade. Estimated prevalence rates of ASD in the U.S. reported by previous data were:

• one in 68 children in the 2014 report that looked at 2010 data