Main Findings Based on tracking in five communities across the United States, we found that the estimated number of children with ASD varied by community, from 8.5 per 1,000 4-year-olds in an area of Missouri to 19.7 per 1,000 4-year-olds in an area of New Jersey. Fewer four-year old children were identified with ASD than eight-year-old in the five communities where CDC tracked ASD. This might be because, even though children can be diagnosed as early as age two years, previous CDC data show that many children with ASD are not diagnosed until after age four years. CDC plans to follow-up with these four-year-old children when they are eight years old to understand more about changes in the number and characteristics of children with ASD as they grow. Four-year-old children identified with ASD were more likely to have intellectual disability than eight-year-old children in the same communities identified with ASD. Among four-year-old children, girls and white children were more likely to receive their first comprehensive, developmental evaluation2 by age three years compared with boys and black children. Researchers looked at the earliest age at which children with ASD had a comprehensive, developmental evaluation.2 They compared the earliest age of evaluation for the four-year-old children (born in 2006) who were diagnosed with ASD by age four with the earliest age of evaluation for the 8-year-old children (born in 2002) who were also diagnosed with ASD by age four. About half of the four-year-old children had an evaluation by the time they were about two years and three months old while about half of the eight-year-old children had an evaluation by the time they were about two years and eight months old. This suggests that children born in 2006 received evaluations at younger ages than children born in 2002. The difference of five months is important because the earlier a child is evaluated, the earlier that child can receive a diagnosis of ASD and be connected to services.
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