“One thing the data tells us with certainty: There are many children and families who need help,” Dr. Thomas R. Frieden, director of the C.D.C., said in a news conference on Thursday.
C.D.C. researchers did not meet any of the children they judged to have an autism spectrum disorder. The team made the decisions based on evaluations of the children, drawn from 14 states. The estimated rates in those states varied widely, from one in 210 children in Alabama to one in 47 in Utah.
“This is a fourfold difference,” Dr. Éric Fombonne, a psychiatrist at McGill University and Montreal Children’s Hospital, said in an e-mail. “It means that ascertainment is unequal across states. Thus, in the next surveys, as ascertainment will most likely improve where it is currently low, average rates are bound to increase. Is there, in addition to this, a real increase in incidence? It’s possible, but cannot be determined from the study design.”
Over all, boys were almost five times as likely as girls to get such a diagnosis — at a rate of one in 54, compared with one in 252 for girls.
The sharpest increases appeared among Hispanic and black children, who historically have been less likely to receive an autism spectrum diagnosis than white children.