Survey of Over 30K Children Reveals the Truth About Our Autism Rates

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Data from the National Health Interview Survey (NHIS) has provided an update on the prevalence of autism in the United States, further solidifying findings that the CDC’s Autism and Developmental Disabilities (ADDM) Network uncovered in 2016: autism rates appear to be stabilizing.

Here’s what happened. In 2014, the NHIS added a new question to their docket: “Has a doctor or health professional ever told you that [the child] has autism, Asperger’s disorder, pervasive developmental disorder, or autism spectrum disorder?”

Over the course of three years—2014 to 2016—the survey collected data about 30,502 kids ages three to 17 living in households across the country. “Yes” was the response in 711 cases.

Photo: Adobe Stock/JackF

Photo: Adobe Stock/JackF

After performing all of their number crunching and statistical magic, researchers from the University of Iowa who evaluated the data came up with the number 2.41 percent. So that’s roughly the prevalence of autism from the years 2014 to 2016.

The numbers did vary slightly on a year-by-year basis. In 2014, the percentage was 2.24; in 2015, it was 2.41; and in 2016, it was 2.58. As you can see, then, the percentages increased year by year.

However, those differences were not considered statistically significant—which basically means they were so small that they don’t really mean anything, and we can pretty much chalk the increase up to chance.

The conclusion we can draw from this, therefore, is that autism rates over that three-year period were stable.

Photo: Adobe Stock/ra2 studio

Photo: Adobe Stock/ra2 studio

There were a few differences between these newest findings and those from the original CDC/ADDM study. For one thing, the NHIS gathered their data by surveying households, whereas the ADDM gathered their data from medical and educational records. However, the NHIS’s research spanned across the country, whereas the ADDM only looked into 11 different communities. The NHIS reported a higher percentage of autistic kids (again, that number was 2.41) than the ADDM (1.47 percent). This may be due to the methodological differences.

However, it’s noteworthy that the CDC’s ADDM and the NHIS both found that autism rates appear to be stable. We must still wait and see whether this plateau will continue before we can say for sure that autism rates have stabilized, but our current statistics—supported by not one but two studies—suggests this might just be the case.

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A. Stout received a Bachelor of Arts in Writing through Grand Valley State University, graduating Magna Cum Laude in 2015. In addition to being a passionate autism advocate, she is a member of various fandoms, a study abroad alumna, and an animal lover. She dreams of publishing novels and traveling all over the world someday.