A new report came out today: Changes in Prevalence of Parent-reported Autism Spectrum Disorder in School-aged U.S. Children: 2007 to 2011–2012. I’ll come back for more detail and discussion soon, but the bottom line: the autism prevalence estimate for the US is now about 2%. 3.23% for boys.
Here is the press release for this:
CDC and HRSA issue report on changes in prevalence of parent-reported
Autism Spectrum Disorder in school-aged children
Who: CDC’s National Center for Health Statistics and the Health Resources and Services Administration
What: “Changes in Prevalence of Parent-Reported Autism Spectrum Disorder in School-Aged Children: 2007 to 2011-2012.”
The report was co-authored by HRSA and data collection was conducted by the CDC. The data come from the National Survey of Children’s Health, a nationally representative phone survey of households with children. This survey is conducted every four years.
Main findings of the report:
· The prevalence of parent-reported ASD among children aged 6-17 years was 2 percent in 2011-2012 compared to 1.2 percent in 2007.
· The change in prevalence estimates was greatest for boys and for adolescents aged 14 to 17 years.
· Children who were first diagnosed in or after 2008 were more likely to have milder ASD than those diagnosed in or before 2007.
· Much of the increase in the prevalence estimates from 2007 to 2011-2012 for school-aged children was the result of diagnoses of children with previously unrecognized ASD.
The report is available at http://www.cdc.gov/nchs.
For information about HRSA’s autism efforts visit http://mchb.hrsa.gov/programs/autism/index.html.
For information about CDC’s autism efforts visit http://www.cdc.gov/ncbddd/autism/index.html.
As indicated above, there are clearly social factors at play involving identification of individuals previously unidentified. For example: If one looks at the prevalence estimate for 6-9 year olds in 2007, a value of 1.31% was obtained. In 2010-11, the prevalence for children born in the same years (now aged 10-13 years old) is 2.39%. In other words, children born in the years 1998-2001 saw an big increase in the estimated autism prevalence.
For the 2010-11 report, about 1/3 of the children were diagnosed after 2008. These are children 6-17 years old, so they were born in 2005 and before. About 30% of children born in 1998-2001 were diagnosed after 2008. These are children aged 7-13.
And, yes, this means that the thimerosal hypothesis, the notion that the increased exposure to thimerosal from vaccines in the 1990’s cause an autism-epidemic, is even less viable. There are obviously a number of social influences behind the increase in autism prevalence estimates in the U.S.. These could mask a “real” increase (or, interestingly, a real decrease). But had thimerosal been a primary driver of the increased prevalence, the prevalence would be dropping. The prevalence for children 6-9 years old, children born after the phase out of thimerosal, now is estimated at 1.82%.
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By Matt Carey
Left Brain Right Brain 
It also leaves the MMR hypothesis pounding sand. MMR coverage has decreased over the last decade. http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6004a1.htm#Tab3
Those claiming that MMR and/or thimerosal caused an autism epidemic were skating on thin ice. To abuse the analogy, that ice melted years ago. This study just raises the temperature of the water a little more.
I’m somewhat disappointed in my colleagues at CDC. They did a poor job of explaining the ins and outs of this survey. Why do independent bloggers have to explain this to the layperson? Why don’t they do it well enough to not leave any doubt that this is a survey, and that surveys do not trump detailed, controlled surveillance systems?
My God, man… Can you imagine if I told you how the flu was going based on only asking people how they felt each week and without any lab data and hospital chart reviews to back up my observations? I’d be out of a job!
That said, thank you for covering this.
Also, Emily Willingham
http://www.forbes.com/sites/emilywillingham/2013/03/20/autism-prevalence-is-now-at-1-in-50-children/
“You will probably see a lot of headlines about the 1 in 50. Some organizations might even try to use those numbers to scare people, to talk about an “epidemic” or a “tsunami.” But if you look at the numbers and the report itself, you’ll see that overall, the numbers of people born with autism aren’t necessarily increasing dramatically. It’s just that we’re getting better and better at counting them. The next step is getting better at accepting autistic people, seeing their potential, and ensuring the supports and resources they need to fulfill that potential.”
I’ve already posted on Emily Willingham’s Forbes blog. Emily stated…
“You will probably see a lot of headlines about the 1 in 50. Some organizations might even try to use those numbers to scare people, to talk about an “epidemic” or a “tsunami.”
Three of the *journalists* at AoA have blogged about the report and surprise, surprise, none of them have have analyzed the report.
Telephone surveys…Ugh.
Dr. Jay Gordon has weighed in…
Dr. Jay has returned to the Ho-Po after several years’ hiatus. He’s pimping his new book and has commented on the new 1 in 50 autism prevalence report. All the usual suspects from the anti-vaccine blogs are posting there. I’ve posted a bunch of comments (still in moderation) at the Ho-Po. Come and join me there.
http://www.huffingtonpost.com/jay-gordon/cdc-one-of-every-fifty-ch_b_2921256.html