On 27 April 2018, the Centers for Disease Control and Prevention (CDC) released new statistics on autism incidence in the USA – the CDC estimated that 1 out of every 59 children has been diagnosed with autism spectrum disorder (ASD) in 2014. This is a fairly large increase over the 2002 numbers when the CDC estimated that 1 in 152 children was diagnosed with ASD. Just because the CDC updated autism statistics does not mean that there’s suddenly an autism epidemic, nor that vaccines are to blame.
Predictably, the anti-vaccine mob was resorting to their full-throated screaming mode about these new stats. And of course, even if you are a dispassionate observer of these numbers, you may wonder why the autism diagnosis rate has nearly tripled from 2002 to 2014.
And that’s why we’re here – let’s examine why and how the CDC updated autism statistics. And I’m going to show you why it’s not a sudden epidemic – it’s better scientific research.
CDC updated autism statistics – what did they say
The report, published in the peer-reviewed Morbidity and Mortality Weekly Report Surveillance Summary, utilizes data from the Autism and Developmental Disabilities Monitoring (ADDM) Network, which is an active public health surveillance system that provides estimates of the prevalence of ASD among children aged 8 years who reside within 11 ADDM sites in the United States. Those sites are in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin (see Note 1). This study updates results from a similar study published in 2010.
The ADDM surveillance is done in two separate phases:
- This phase consists of analyzing anonymized comprehensive evaluations of children performed by professional healthcare providers in that community. They use data sources from general pediatric health clinics along with specialized programs for children with developmental disabilities. Additionally, the ADDM network may also review records of special education students in public school
- This phase determines if the child’s case meets the definition of ASD. A child meets the definition if a comprehensive evaluation by a qualified healthcare professional describes behavior consistent with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) (see Note 2). They included diagnoses for the following conditions – autistic disorder, pervasive developmental disorder-not otherwise specified (including atypical autism), or Asperger disorder.
For 2014, the overall prevalence of ASD among the 11 ADDM sites was 16.8 per 1,000 (one in 59) children aged 8 years. Overall ASD prevalence estimates varied among sites, from 13.1-29.3 per 1,000 children aged 8 years.
This study from the CDC updated autism statistics to a level that seems that autism is growing quickly in the USA. But is it really?
The autism non-epidemic
Despite some of the nonsense floating up from the bowels of the anti-vaccine religion, we need to find logical and scientific reasons why the autism diagnosis rate increase from 1 in 152 children in 2002 to 1 in 59 children in 2014 (See Note 3). We’re going to rely upon Occam’s razor for this analysis – the best answers to the question, “is this an epidemic,” should be the ones with the fewest assumptions to get to the answers.
First of all, we should take a much closer look at the data. There is a statistically significant geographical disparity in diagnosis rates. For example, New Jersey has the highest incidence of ASD, while Arkansas has the lowest. Is that because NJ has more autistic children because of reasons? No, there’s a simpler reason – NJ has a much better healthcare system than Arkansas. New Jersey ranks 12th and Arkansas 49th on the list of healthcare quality in the USA. Ready access to high-quality healthcare is important to proper diagnosis of ASD.
Some of the increase can be explained by the closing of racial disparities in proper healthcare access to accurate diagnosis of ASD. In the 2002 and 2010 CDC reports, white children were 20-30% more likely to receive an ASD diagnosis than black children. Moreover, white children were about 50% more likely to get that diagnosis as Hispanic children. That’s more of an indictment about the availability of healthcare services to white children as compared to blacks and Hispanics. The data doesn’t say that black and Hispanic children are less susceptible to ASD.
Furthermore, there has been a serious inconsistency in the diagnosis of ASD by race. For example, children of color are often diagnosed at later ages than white children. Also, children of color are often overdiagnosed with learning disabilities and emotional problems, rather than receiving a diagnosis of ASD.
But it gets worse. There are also similar disparities in ASD diagnosis by gender. The 2002 report stated that 1 in 42 boys and 1 in 189 girls were diagnosed with ASD, a 4.5:1 ratio. The 2014 report showed it was 4:1 ratio. We can either believe that boys are more susceptible to ASD or, more probably, there is substantial evidence that significant gender bias leads to a remarkable under-diagnosing of ASD in girls and women. Instead of showing me that there’s an autism epidemic, it’s showing me that healthcare has a fundamental problem with gender bias. However, proper diagnosis of girls appears to be improving and, by the way, adding to the new and higher CDC updated autism statistics.
What does this all mean? Well, there are several important factors that are leading to the much higher incidence of diagnosis:
- Better diagnostic criteria available to professional healthcare providers, including improved mental health systems within managed healthcare organizations.
- A reduction in racial and sex disparity in diagnosis, which means the total number of diagnoses is increasing because a huge group of children was under-diagnosed.
- States with better healthcare access are increasing diagnoses of ASD faster than states with poorer access – but overall there is more availability to proper diagnosis across the USA.
Before we can jump up and down, screaming “autism epidemic,” we need to establish if there really is an epidemic. All I can see from the data is that the baseline keeps changing. We are improving the diagnostic criteria. We are reducing racial and gender bias. And we are improving mental health access for children, at least in some areas of the country. If we can establish a baseline incidence for ASD, then maybe we can determine if there’s a change. Instead of so-called autism advocacy groups would spend less money on the anti-vaccine nonsense, and more on actually improving autism diagnosis and treatment, we would stop this “epidemic” talk.
And even though ASD diagnosis rate seems high, it still means that 97 out of 100 American children are not diagnosed with ASD. And compared to other mental health diagnoses, the incidence of ASD is still 3-4X lower than many other mental health disorders (see Note 3).
The CDC updated autism statistics, so vaccines
Uh no. It’s not vaccines. We have robust evidence that has demonstrably shown that vaccines are not linked to ASD. This is settled science, and unless someone brings the world evidence of similar quality and quantity that supports a hypothetical link between vaccines and autism, it’s time to move on.
We have lots of evidence of what may be the underlying cause of autism, and, once again, it’s not vaccines.
We can safely conclude that there is not an autism epidemic. And we can be quite sure that vaccines have nothing to do with the autism.
Yes, the CDC updated autism statistics, and they show a much higher number than the past. But the problem with comparing current data to the past is that there are numerous important variables that have a significant impact on the increased numbers – racial and gender bias in the past, variable healthcare access, and improved diagnostic criteria. We have yet to establish a baseline incidence of ASD – until that time, false “epidemic” claims are detrimental to future research to find that baseline.
It’s clear that ASD is a significant mental health issue which requires the focus of the public health system. But calling it an epidemic and falsely blaming vaccines is not helpful to finding real causes and real treatments. We should focus on the children, not on this tiresome and absolutely useless scaremongering and blame.
- In case you were wondering why only 11 sites, like most surveillance systems, it uses a statistically robust sampling system. These 11 states represent a diverse economic and cultural populations, which help reducing confounders. Although one might think that having data from every county in the USA is preferable, it is cost prohibitive. Proper, and unbiased, statistical sampling is usually very accurate.
- The DSM-IV-TR was replaced by the DSM-5 in 2013, which meant that this 2014 study was right on the cusp of the changeover to the new diagnostic criteria, which changed some aspects of the ASD diagnosis. Probably most psychiatrists and psychologists had made the change during the timeframe of this study. Starting in 2016, the ADDM network will use the DSM-5 criteria.
- We should put the 1 in 59 diagnoses in context with other mental health issues. For example, 1 in 38 Americans has been diagnosed with bipolar disorder. And, 1 in 15 has major depressive disorder. All mental health issues have a high incidence as a result of better diagnosis and intervention.
- Autism and Developmental Disabilities Monitoring Network Surveillance Year 2002 Principal Investigators.; Centers for Disease Control and Prevention.. Prevalence of autism spectrum disorders–autism and developmental disabilities monitoring network, 14 sites, United States, 2002. MMWR Surveill Summ. 2007 Feb 9;56(1):12-28. PubMed PMID: 17287715.
- Baio J, Wiggins L, Christensen DL, Maenner MJ, Daniels J, Warren Z, Kurzius-Spencer M, Zahorodny W, Robinson Rosenberg C, White T, Durkin MS, Imm P, Nikolaou L, Yeargin-Allsopp M, Lee LC, Harrington R, Lopez M, Fitzgerald RT, Hewitt A, Pettygrove S, Constantino JN, Vehorn A, Shenouda J, Hall-Lande J, Van Naarden Braun K, Dowling NF. Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years – Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014. MMWR Surveill Summ. 2018 Apr 27;67(6):1-23. doi: 10.15585/mmwr.ss6706a1. PubMed PMID: 29701730.
- Developmental Disabilities Monitoring Network Surveillance Year 2010 Principal Investigators.; Centers for Disease Control and Prevention (CDC).. Prevalence of autism spectrum disorder among children aged 8 years – autism and developmental disabilities monitoring network, 11 sites, United States, 2010. MMWR Surveill Summ. 2014 Mar 28;63(2):1-21. PubMed PMID: 24670961.
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