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The CDC Calculates the Prevalence of Autism

In the United States, the Centers for Disease Control conduct a study every two years to establish the prevalence of autism in children. I have criticized the methodology in other venues, especially because the media leaps on the subject with vigor.

Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years–Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012

The Autism and Developmental Disabilities Monitoring (ADDM) Network is an active surveillance system that provides estimates of the prevalence and characteristics of ASD among children aged 8 years whose parents or guardians reside in 11 ADDM Network sites in the United States (Arkansas, Arizona, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, South Carolina, Utah, and Wisconsin).

See also: ADDM Network Community Report

This is the latest researched report, and is the source of the false fact that one in 68 children in America are autistic.

  1. The data was released in 2016, and dates to 2012. It cannot be termed “current data”.
  2. The number of children in the 11 states studied, age 8, was 346,978. The study suggests that 14.6 per 1,000 (one in 68) were autistic. That works out to 5,103 children on the spectrum. The CDC reports that 4,112,052 children were born in 2004, making them eight years old in 2012. The sample studied is “about” eight percent of the total number of children age 8. As reported, however, the sample has a questionable makeup.
  3. Prevalence is influenced by geography. In New Jersey, the autism rate was 1:41. In South Carolina, the rate was 1:81.
  4. Prevalence is influenced by biological sex. Boys were 4.5times more likely to be diagnosed autistic than girls.
  5. Prevalence is influenced by race. White children are diagnosed as autistic 1.2 times more often that black children and 1.5 times more often than Hispanic children.

The study suggests, as it has for several iterations, that autism is a condition found in white boys attending school along the East Coast.

Notice that the four most populous states, California, Texas, Florida, and New York, are not included in the study. The study excludes states with significant metropolitan populations, as well as states with significant Hispanic populations. The sample cannot be termed at all adequate for reaching conclusions about the United States as a whole. The authors recognize this but it is ignored by the media and by autism advocates.

The 2014 National Health Interview Survey is touted as the source of a newer statistic, that the prevalence of autism was 1 in 45 children in 2014. Much was made of the increase.

The CDC notes that the data from the two documents cannot be compared. The survey consists of self-reported data, using a new set of questions from prior surveys. It found that the prevalence of autism for 2014 was 2.24 percent of the entire population ages three to 17. It also found that the number of developmental disabilities dropped about 26 percent in the two years since the last survey.

The conclusion to be drawn from the 2014 survey is that the “label”, or diagnosis, for the child is changeable for parents. Requiring one “label” mandates the parent choose between a number of diagnoses and does not produce data reflecting co-morbid conditions that often are found along with autism.

What is the prevalence of autism in the United States? No one knows. Is that number growing? No one knows. If your focus is on the prevention of autism or curing autism, those statements provide little comfort.

One final takeaway from this discussion should be that the variances point to differences in medical diagnosis, treatment for co-morbid conditions, and education accommodations, that have long concerned both families and those with autism.

Published inResearch