The thimerosal/autism study by Thomas Verstraeten is one of the big targets for those with the vaccines/mercury cause autism agenda. For what it’s worth, Autism’s False Prophets goes into the history of the Verstraeten study and clearly explains the history of that study. Not surprisingly, the answer is somewhat different than you might find in, say, Evidence of Harm.
In his recent briefing on Capital Hill, David Kirby took another jab at the Verstraeten study. He tried to assert that (a) the NIEHS claimed that the Vaccine Safety Datalink was unusable for autism studies and that (b) the CDC agreed. He was incorrect, and, luckily, a staffer caught Kirby at it.
Mr. Kirby is trying to explain his actions in a blog post in which he posts an open letter to that congressional staffer.
Let’s consider something here: the congressional staffer, an M.D., knew enough about the subject to catch David Kirby misquoting the NIEHS. I wouldn’t have been quick enough on my feet to catch the misquote. Now, David Kirby wants to educate this gentleman. Frankly, the information should be flowing the other way. If Mr. Kirby had shown himself open to such education, say when EpiWonk made it abundantly clear (twice) what Mr. Kirby’s mistakes were, perhaps it would be worth the staffer’s time to discuss this with Mr. Kirby. That said, let’s take a look at Mr. Kirby’s letter.
In regards to Mr. Kirby’s misquotes, he has recently “clarified” his position. He is writing to the Doctor who corrected him in his briefing here:
As you rightly pointed out (and as I concurred that day) I omitted an important detail in regards to Dr. Gerberdings’s letter to the Committee. I regret that, and never meant to mislead people in the room.
It was a rather artless sin of omission.
I think the lesson for me here is that, when you try to cram a two hour presentation into 25 minutes, it is wise to not include very complicated and, as you put it, “somewhat arcane” details that are difficult to explain in such a short period of time. In retrospect, I probably should have focused solely on the NIEHS report itself, and left the Gerberding letter out of the presentation entirely.
Mr. Kiby iscorrect, it is a confusing situation. There are two documents–an NIEHS report and Dr. Gerberding’s response for the CDC. But, does that excuse misquoting the head of the CDC in his legislative briefing?
Here’s what David Kirby in his capital hill briefing “quoted” the NIEHS report as saying:
NIH: “We identified several areas of weakness that were judged to reduce the usefulness of the VSD for addressing the potential association between exposure to thimerosal and risk of ASD.”
That isn’t in either the NIEHS report or Dr. Gerberding’s response. Here’s what Dr. Gerberding actually agreed to:
The panel identified several serious problems that were judged to reduce the usefulness of an ecologic study design using the VSD to address the potential association between thimerosal and the risk of AD/ASD.
Emphasis is mine. But, we’ve already discussed that: Dr. Gerberding didn’t claim that the VSD has reduced usefulness in addressing the thimerosal/autism question. It made a claim that the ecological studies using the VSD had limitations. But, the recipient of Mr. Kirby’s letter would know that.
Back to Mr. Kirby’s open letter: David Kirby is now presenting his own interpretation of the NIEHS report, in place of Dr. Gerberding’s.
As I interpret things, the panel concluded that the database itself suffered from several weaknesses and limitations, which in turn reduced its usefulness for studies of autism risks from thimerosal (ie, Verstraeten) AND ALSO reduced the feasibility of future studies (ie, ecological ones) that are based on data collected within the VSD.
As EpiWonk aptly pointed out, Mr Kirby’s assertion is not the case. The NIEHS panel suggested a number of possible studies on autism using the VSD. From the NIEHS report:
An alternate future study design that was viewed positively among panel members was a study of a high risk population, defined, in this instance, as siblings of individuals diagnosed with AD/ASD. A sibling cohort from the VSD would allow comparison of AD/ASD risk in siblings as a function of their thimerosal exposure through vaccination and the sample size would lend itself to supplemental data collection. A related study design based on sib-pairs or sets could be used to address discordant ASD/AD status in relation to thimerosal exposures. Another possibility that generated support by the panel was an expansion of the VSD study published by Verstraten et al (2004). The availability of several additional years of VSD data was seen as an opportunity to provide a more powerful test of any potential association between thimerosal and AD/ASD and would enable reconsideration of some aspects of the original study design (e.g., exclusion criteria). A related idea was to conduct a VSD retrospective cohort study using California-based MCOs linked with the California DDS, which would improve the diagnostic data and provide more complete ascertainment. For each of these designs, the ability to link medical records from mothers with those of their children was deemed critical.
As this reader interprets things, NIEHS seems to find that there is quite a bit of value in the VSD for studying autism, including an expansion of the Verstraeten study.
EpiWonk made the point first, but how can the NIEHS say that Verstraeten study design is not a good and that future use of the VSD is not useful, while at the same time suggest expanding Verstraeten?
The bottom line is that there are limitations to using the VSD alone in ecological studies of autism. One can overcome these limitations by going to chart reviews and other methods–as used in Verstraeten et al. and, more importantly, by VSD studies ongoing at CDC (one of which looks at autism). As noted by Dr. Gerberding:
The VSD currently has a number of priority studies underway to address a range of important immunization safety questions, none of which utilize an ecologic study design. Instead, these current studies, including one study evaluating associations between thimerosal-containing
vaccines and autism, all evaluate individual-level data. This typically involves the review of individual medical charts to confirm the vaccines each individual received as well as the outcomes being studied. Studies using individual rather than group data provide stronger scientific evidence.
Mr. Kirby seems to be neglecting the fact that the CDC’s ongoing study (and the Verstraeten study) is not soley dependent on the VSD for the data. He seems to be arguing that since the VSD, as a single data source, has limitations, the CDC can’t use it for any study. It’s like saying,
But, let’s take a closer look at what this says….and what Mr. Kirby is saying: The VSD on it’s own is not a good source of data to look at the thimerosal/autism question.
Now, anyone remember all the consternation that has been created by the fact that the VSD is not open to just any outside researcher? Why should the VSD be opened to, say, Mark and David Geier? Could they do the individual level data collection needed to make a VSD study valuable?
Apparently not. Recall this study by the Heather Young and the Geiers: Thimerosal exposure in infants and neurodevelopmental disorders: An assessment of computerized medical records in the Vaccine Safety Datalink
The recent Heather Young/Geier paper didn’t look at individual level data. Any future study by the Geiers almost certainly wouldn’t as well. Given the argument by the NIEHS, Dr. Gerberding…and David Kirby, the above study and any proposed study by the Geiers on the VSD would be useless.
Some how I doubt Mr. Kirby will make statements confirming that. But, I can’t see how he could hold any other opinion, given the arguments he, himself, has made.