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Autism prevalence rose among preschoolers from 2010 to 2014

The prevalence of autism spectrum disorder was higher in 2014 than in 2010 among children aged 4 years, according to CDC data from the Early Autism and Developmental Disabilities Monitoring Network.

“Measuring ASD prevalence and age at diagnosis in elementary school-aged children is expected to yield the most complete information on ASD prevalence and characteristics; however, measuring ASD prevalence in preschool-aged children provides more timely assessment of efforts to increase awareness and early detection of ASD,” Deborah L. Christensen, PhD, from the CDC’s National Center on Birth Defects and Developmental Disabilities, and colleagues wrote in Morbidity and Mortality Weekly Report.

In this study, researchers collected 2010, 2012 and 2014 data from the Early Autism and Developmental Disabilities Monitoring (Early ADDM) Network.

This surveillance system provides estimates of ASD prevalence, trends and characteristics among children aged 4 years living within designated sites in Arizona, Colorado, Missouri, New Jersey, North Carolina, Utah and Wisconsin. The report included data on age at first developmental evaluation, age at diagnosis and cognitive function, as well as comparisons with children aged 8 years living in the same area. Analyses of time trends in ASD prevalence were restricted to Arizona, Missouri and New Jersey.

The ASD prevalence increased overall among children aged 4 years from 13.4 per 1,000 children in 2010 to 15.3 in 2012 to 17 in 2014 across the Early ADDM sites, according to the results. ASD prevalence varied within each surveillance year; the prevalence was highest for New Jersey (19.7, 22.1 and 28.4 per 1,000 for 2010, 2012 and 2014, respectively), and lowest for Missouri (8.5, 8.1 and 9.6 per 1,000 for 2010, 2012 and 2014, respectively).

Christensen and colleagues found that ASD prevalence among children aged 4 years was consistently higher among boys than girls across all sites and years. They also found that ASD prevalence was higher among white children than Hispanic children in Arizona and black children in Missouri in 2010, but there were no other differences observed by race/ethnicity.

In Arizona, New Jersey, North Carolina and Utah, the frequency of co-occurring intellectual disabilities was significantly higher among children aged 4 years than among children aged 8 years in each surveillance year, apart from Arizona in 2010. The ASD prevalence estimates were higher for sites that reviewed education and health care records than for those that reviewed only health care records, according to the data.

The researchers also observed that the trends in ASD prevalence were higher in 2014 than in 2010 among children aged 4 years in New Jersey but remained stable in Arizona and Missouri. Prevalence of ASD was higher among children aged 8 years than among those aged 4 years in Missouri only.

“Continuing improvements in providing developmental evaluations to children as soon as developmental concerns are identified might result in earlier ASD diagnoses and earlier receipt of services, which might improve developmental outcomes,” Christensen and colleagues wrote. – by Savannah Demko

Disclosures: Christensen report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.