Autism Street

In a recent article at his Huffington Post blog, David Kirby comments on recent word that the HHS would revise it’s estimates of prevalence for autism spectrum disorders, based on new data for the 1996 birth year cohort. Not surprisingly, Kirby had questions. Also not surprisingly, even though he essentially discards Thimerosal and MMR, his question boils down to vaccines. From his post (a question he apparently attempted to ask on a conference call with the NIMH director, Dr. Thomas Insel).

Note: there are now two very different versions - David Kirby apparently revised his post after I’d read it, and cut and pasted the relevant part of the first version a little over a week ago.

Here are both versions. I don’t know when the post was actually changed.

Version 1

And so, here is my (expanded) question, directed to Dr. Insel:

Dr. Insel, thank you for arranging this call. I understand that the estimated average ASD rate increased from 66-per-10,000 to 100-per-10,000 between the 1994 and 1996 birth cohorts. Officials on this call believe this increase could be attributed purely to expanding diagnostic criteria and greater awareness, though they don’t know for sure.

But how could you attribute a 50% increase in just two years to wider diagnostics, especially when the 1994 cohort would have been diagnosed, on average, in 1998 and the latter cohort in 2000? The expansion of the ASD definition to include Asperger and PDD-NOS occurred in the early 1990s, so how can you explain this sudden and delayed explosion in the numbers?

Also, you have declared that the vaccine-autism link had been disproven, yet all the studies you cite have only looked at MMR and thimerosal. But why is the IACC, which you chair, not investigating the possible role of Hep-B vaccine, given the following facts:

1) For the 1994 birth cohort, Hepatitis-B vaccine was given to 27% of all newborns, but in 1996 it had jumped to 82%. (HERE)

2) An abstract just published in the Annals of Epidemiology said that giving Hepatitis B vaccine to newborn baby boys more than triples the risk of ASD. (HERE)

3) A study just published in Neurotoxicology reported that infant male primates who received one dose of Hepatitis-B vaccine were far more likely to display developmental delays than unvaccinated controls. (HERE)

4) A study last year in Toxicological and Environmental Chemistry showed that boys getting the 3-shot HepB vaccine series were eight times more likely to require early intervention services than boys who did not have the series. (HERE)

5) A study in the journal Neurology found that children who received the Hepatitis B vaccine series were 50% more likely to develop “central nervous system inflammatory demyelination” than children who did not receive the vaccine. (HERE)  

Finally, why does your committee ignore evidence associating heavy metals and other toxins with ASD, why did you jettison the vaccinated-vs.-unvaccinated study that your own committee had previously voted to recommend, and why are you spending only 39 minutes speaking with the community that represents, according to your boss, one of the nation’s “top health priorities?”

I am also sending this question to HHS, to see if I can get a proper response. But I am not holding my breath.

Version 2

And so, here is my (expanded) question, directed to Dr. Insel:

Dr. Insel, thank you for arranging this call. I understand that the estimated average ASD rate increased from 66-per-10,000 to 100-per-10,000 between the 1994 and 1996 birth cohorts. Officials on this call believe this increase could be attributed purely to expanding diagnostic criteria and greater awareness, though they don’t know for sure.

But how could you attribute a 50% increase in just two years to wider diagnostics, especially when the 1994 cohort would have been diagnosed, on average, in 1999 and the latter cohort in 2001? The expansion of the ASD definition to include Asperger and PDD-NOS occurred in the early 1990s, so how can you explain this sudden and delayed explosion in the numbers?

Also, you have declared that the vaccine-autism link has been disproven, yet all the studies you cite have only looked at MMR and thimerosal. But why is the IACC, which you chair, not investigating the possible role of Hep-B vaccine, given the following facts?:

1) An abstract just published in the Annals of Epidemiology said that giving Hepatitis B vaccine to newborn baby boys more than triples the risk of ASD.

2) A study just published in Neurotoxicology reported that infant male primates who received one dose of the Hepatitis-B were far more likely to display developmental delays than unvaccinated controls.

3) A study last year in Toxicological and Environmental Chemistry showed that boys getting the 3-shot HepB vaccine series were eight times more likely to require early intervention services than boys who did not have the series.

4) A study in the journal Neurology found that children who received Merck’s Engerix B brand Hepatitis B vaccine series were 74% more likely to develop “central nervous system inflammatory demyelination” than children who did not receive the vaccine.

Finally, why did you jettison the vaccinated-vs.-unvaccinated study that your own committee had previously voted to recommend, and why are you spending only 39 minutes speaking with the community that represents, according to your boss, one of the nation’s “top health priorities?”

I am also sending this question to HHS, to see if I can get a proper response. But I am not holding my breath.

I’m not particularly interested in irrelevant and likely misleading (newborn vs. 3-shot Hep B series numbers) that Kirby has apparently removed from his original post.

His numbers looked like something he made up (to me anyway), and the link he provided was not to any actual data. Contrary to the misinformation provided in version 1 of Kirby’s post, Hep B vaccination coverage (for the entire 3-shot series) was already 82% for the majority of the 1994 birth year cohort! I’m not sure which data David Kirby was using in his non-specific link, but you don’t have to take my word for it.

37% Hep B vaccine coverage was already seen in the group closest to the 1992 birth year cohort (NIS, 19-35 month-olds in 1994).

http://www.cdc.gov/mmwr/preview/mmwrhtml/00038532.htm

82% Hep B vaccine coverage was seeen in the group closest to the 1994 birth year cohort (NIS, 19-35 month-olds in 1996).

http://www.cdc.gov/mmwr/preview/mmwrhtml/00048503.htm

87% Hep B vaccine coverage was seeen in the group closest to the 1996 birth year cohort (NIS, 19-35 month-olds in 1998).

http://www.cdc.gov/mmwr/preview/mmwrhtml/ss4909a1.htm

(Edite to add: Kirby was smart to eliminate his original post’s reference to increased Hep B vaccine coverage if he wants to keep a “Hep B vaccine causes autism hypothesis alive”. The data wouldn’t support it. Hep B vaccine coverage went from 8% to 82% between 1992 and 1996 - full three-shot series.  Autism “numbers” during that time of increase? Probably not too favorable to his hypothesis).

I’m also not too interested abstracts of unpublished papers.

I’m not terribly interested in totally irrelevant-to-autism citations that seem to attempt to redefine “developmental delays” in the context of autism either. Some might call it “Monkey Business“.

Not-specific-to-autism-at-all survey information? Yawn.

“CNS inflammatory demyelination”? Is David Kirby an idiot, or what? The paper he linked to concludes with the following:

The rates of HB vaccination in the 3 years before the index date were 24.4% for the 349 cases and 27.3% for their 2,941 matched controls. HB vaccination within this period was not associated with an increase in the rate of CNS inflammatory demyelination (adjusted OR, 0.74; 0.54–1.02), neither >3 years nor as a function of the number of injections or brand type. When the analysis was restricted to subjects compliant with vaccination, HB vaccine exposure >3 years before index date was associated with an increased trend (1.50; 0.93–2.43), essentially from the Engerix B vaccine (1.74; 1.03–2.95). The OR was particularly elevated for this brand in patients with confirmed multiple sclerosis (2.77; 1.23–6.24).

Conclusions: Hepatitis B vaccination does not generally increase the risk of CNS inflammatory demyelination in childhood.

Emphasis mine.

Wow, Kirby’s #4 (#5 in the old post) looks like an outright lie - but I suppose it could be sheer ignorance. The linked study found no association when comparing children based on vaccination status, although Kirby claimed otherwise. What it did find was an increased odds ratio amongst the smaller vaccinated-only percentage (the study was in France), predominantly in confirmed Multiple Sclerosis patients. Relevance to autism? None!

The part of Kirby’s original post that did interest me, was this one:

But how could you attribute a 50% increase in just two years to wider diagnostics, especially when the 1994 cohort would have been diagnosed, on average, in 1998 and the latter cohort in 2000? The expansion of the ASD definition to include Asperger and PDD-NOS occurred in the early 1990s, so how can you explain this sudden and delayed explosion in the numbers?

Here’s what I’d written about his first version about a week ago, but not yet had a chance to publish:

“Actually, the inclusion of PDD-NOS (which along with Asperger Syndrome, accounts for about two-thirds of all autism spectrum disorder diagnoses) occurred in 1987, not the early 1990’s. Additionally, Kirby has correctly noted that Asperger Syndrome was added in the early 1990’s (1994), but he’s failed to mention that the criteria for autistic disorder itself were greatly expanded (to be less restrictive) in 1994 too!

Why on earth would I point out Kirby’s error about PDD-NOS, and omission with respect to to expansion of the criteria for autistic disorder, when it would appear to support his point that an “explosion in numbers” was delayed and sudden? It’s because the notion that this increase was delayed and appears sudden is not surprising, and probably irrelevant. Here’s the bottom line - The specific diagnoses that account for nearly a full two-thirds of all autism spectrum disorder diagnoses weren’t added to the DSM until 1987 and 1994. Additionally, the specific diagnosis that accounts for the other third of all autism spectrum disorder diagnoses, saw its criteria revised to be much more inclusive in 1994. We should expect that a significant increase (ceterus paribus) will follow 1994!

But what about David Kirby’s notion that the increase was delayed? He asserts, with the numbers, that the average age of an ASD diagnosis at the time would have been about 48 months (1998 for for 1994 birth year cohort, and 2000 for the 1996 birth year cohort), but is that really accurate? Here’s the deal, it IS likely that the average age at diagnosis for autistic disorder was pretty close to 48 months (actually, about 3 and a half years of age) at the time, but Kirby has missed the point of the very question he himself asked! He wants to know how an increase in ASD numbers could be delayed, with the additions of PDD-NOS and Asperger Syndrome in “the early 1990’s”.

Apparently, David Kirby completely failed to put together an accurate premise for his first post. The average age of diagnosis for PDD-NOS for the birth year cohort in 1994 is likely much closer to 4.6 years, and the average age of diagnosis for Asperger Syndrome for the birth year cohort in 1994 is likely closer to 7.5 years. Of course an increase due to the addtions of PDD-NOS and Asperger Syndrome was delayed beyond 4 years - in 1998 the average age of diagnosis was well above 48 months! Yes, those numbers are not really even close to Kirby’s, but that’s not all. Watch what happens when we look at age of diagnosis for the 1996 birth year cohort: PDD-NOS likely around 3.6 years, and Asperger Syndrome likely around 5.4 years! So between the 1994 and 1996 birth year cohorts, the average age of diagnosis for both PDD-NOS and Asperger Syndrome plummets! Don’t forget, PDD-NOS and Asperger Syndrome account for about two-thirds of all autism spectrum disorder diagnoses. I could be wrong, but I’m inclined to think that increased awareness and recognition are probably largely responsible for these decreasing ages of diagnosis.

As a starting point, see (Mandel et al., 2005) for more on age of diagnosis, if you’re interested.

Factors Associated With Age of Diagnosis Among Children With Autism Spectrum Disorders
PEDIATRICS Vol. 116 No. 6 December 2005, pp. 1480-1486
http://pediatrics.aappublications.org/cgi/content/full/116/6/1480

So, A) the increase is expected, and B) for contribution by the additions of PDD-NOS and Asperger Syndrome, delay well beyond 48 months is also expected.

Having failed to consider these points, Kirby launched into a predictible “vaccines dunnit” indictment of the HepB vaccine. ”

But, now, David Kirby has changed his original claim/question:

But how could you attribute a 50% increase in just two years to wider diagnostics, especially when the 1994 cohort would have been diagnosed, on average, in 1999 and the latter cohort in 2001? The expansion of the ASD definition to include Asperger and PDD-NOS occurred in the early 1990s, so how can you explain this sudden and delayed explosion in the numbers?

The second version is a little safer by the numbers for Kirby, as he’s now in the ballpark of a little bit closer to correct about average age of diagnosis at the time, but my point is unchanged. Kirby has ignored the fact that it is expected that any increase based on the inclusion of PDD-NOS and Asperger Syndrome will be delayed (and very real) when you consider the changes in average age of diagnosis for the years in question. Don’t forget about that broadening of the criteria for autism itself in 1994 that Kirby doesn’t mention, it’s likely to have had an impact as well. It wouldn’t hurt to consider the likely impact of the adoption of new diagnoses in practice either - I’m pretty sure those things don’t happen overnight.

As for Kirby’s closing indignation, I’ll just make a few short comments.

They’re probably ignoring so-called “evidence” of an association between heavy metals (and other toxins) and ASD, because the evidence-to-date, is not what the anti-vaccine folks believe it to be. See the recent decisions by the Special Masters in the United States Court of Federal Claims’s Omnibus Autism Proceeding re the state of the science.

They’ve probably let go of the vaccinated vs. unvaccinated study idea due to ethics and feasibility considerations (not to mention the dearth of scientific evidence that suggests such a study would even be fruitful), but I suppose it’s possible that they’re simply growing tired of the wasted time and resources demanded by the anti-vaccine groups.

David Kirby, you and the anti-vaccine groups, are NOT TEH autism community!