Mar 16 2010

Autism Omnibus Hearings – Part II

I love a good sequel. Aliens, of course, was the best sequel ever – that rare event when the sequel is actually better than the original movie (of course, the series went down hill from there, like Star Trek it peaked with the second movie).

Last year we heard the results of the Autism Omnibus – a special court with three special masters set up to resolve about 5,000 cases before the vaccine court claiming that autism resulted from vaccines – either the MMR vaccine or thimerosal (a mercury-based preservative in some vaccines, but removed from most by 2002). In the US there is a Vaccine Injury Compensation Program (VICP) which bypasses the regular courts and awards compensation to those injured by vaccines, paid for by a small tax on each dose of vaccine given. The purpose is to rapidly compensate those who might have been injured (the threshold for evidence is quite low) and to encourage pharmaceutical companies to manufacture vaccines (the threat of suit would make it not viable otherwise).

Over 2008 the Autism Omnibus heard three cases that were presented as the test cases (presumably the best cases they could come up with) for the theory that the  MMR vaccine (with or without thimerosal from other vaccines – MMR never had thimerosal) caused or contributed to autism in some individuals. They ruled against all three cases, stating in very strong terms that there is no evidence to back up the claims of a link between MMR and autism. Judge Hasting wrote of one case – Cedillo:

Considering all of the evidence, I found that the petitioners have failed to demonstrate that thimerosal-containing vaccines can contribute to causing immune dysfunction, or that the MMR vaccine can contribute to causing either autism or gastrointestinal dysfunction. I further conclude that while Michelle Cedillo has tragically suffered from autism and other severe conditions, the petitioners have also failed to demonstrate that her vaccinations played any role at all in causing those problems.

This was a huge blow to the anti-vaccine crowd, and an excellent victory for science and reason. It was the equivalent of the Kitzmiller vs Dover trial for Intelligent Design.

In fact, it reinforced my respect for the judicial process in hearing scientific cases. Stephen J. Gould once observed (I think in reference to Creation Science trials of the 1980s – and I am paraphrasing) that when there are rules of evidence, science generally triumphs over pseudoscience. Pseudosciences, like anti-vaccine nonsense, intelligent design/creationism, and homeopathy – do not fare well when their shenanigans are inspected under the patient and penetrating glare of a thorough trial. Pseudosciences depend upon cherry picking evidence, using logical fallacies, distraction and diversion – all tricks which are exposed by a court following rules of evidence and logic, and taking the time to review all the evidence. We now have a series of high-profile cases in which Gould’s observation is confirmed.

Of course, we always worry that such cases will be decided on matters of law rather than matters of evidence, and then be misinterpreted as confirmation of the pseudoscience. This happened in the 1980s when chiropractors were successful in a restraint of trade suit against the AMA, and then later claimed this was a vindication of chiropractic (it wasn’t). But that’s another story.

In any case, generally science does well in controlled settings, and this past week we saw another example. The Autism Omnibus Court rendered their second set of decisions regarding the next three test cases – this time focusing on the hypothesis that thimerosal causes autism. In all three cases they ruled solidly against the petitioners, stating that they did not make their case. The ruling was not just negative – like the Dover decision, it was a harsh condemnation of the case put forward by the lawyers for the petitioners.

You can read the full decisions here: George and Victoria Mead, Fred and  Mylinda King,  and Timothy and Maria Dwyer. While expressing sympathy for the parents and their children, the masters ruled against every aspect of the case they brought forward. For background, autism is an “off table” injury claim – there is no presumption of causation, but petitioners must demonstrate their case with a “preponderance of evidence.” This is a lower standard than would be used in science, and the decision is limited to whether or not compensation is appropriate – not the ultimate scientific conclusion.

Here are some highlights from the decisions:

Support for petitioners’ claim does not come from the epidemiologic evidence, and petitioners’ claim that the performed studies lack the requisite specificity to detect an association between the receipt of thimerosal-containing vaccines and the allegedly small subset of cases involving autism with clear signs of regression is unavailing.

Petitioners have not shown either that certain children are genetically hypersusceptible to mercury or that certain children are predisposed to have difficulty excreting mercury. The scientific validity of the studies on which petitioners rely has been
questioned and the conclusions drawn from the studies have been criticized as unsupported.

While petitioners have alleged correctly that inorganic mercury can remain in the brain for a period of time, petitioners have not shown that the inorganic mercury deposited in the brain–in the amount that could be received from a full complement of thimerosal containing vaccines–can cause the effects that petitioners have alleged.

If you will excuse a somewhat longer excerpt, this section on the claim that response to treatment with chelation proves mercury caused autism, is a good example of the kind of analysis used in the hearing:

Respondent’s experts Dr. Rust and Dr. Fombonne argued persuasively that it would be inappropriate to draw any inferences concerning causation, in Jordan’s case or any case, from Dr. Mumper’s testimony concerning treatments, for several reasons. First, they pointed out that the treatments to which Dr. Mumper referred have not been demonstrated by scientific testing to have any beneficial effects on autism in general. Dr. Brent provided similar testimony.

Second, respondent’s experts explained that autistic children quite often have periods of substantial improvement in their symptoms in the absence of any treatment, so that it is not reasonable to conclude that a particular period of improvement was caused by any recent treatment.

Third, respondent’s experts noted that because Jordan was often subjected to more than one treatment at a time, it is even more dubious to ascribe any improvements to particular treatments. (Ex. M, paras. 46, 142-43; Tr. 2459-60, 3697-99.)
Moreover, it is clear that chelation treatments do not remove mercury from the brain, so it is not logical to conclude that such treatment could affect autism.

In this regard, on cross-examination Dr. Mumper herself acknowledged that she could not 108 explain how the other treatments upon which she relied could, even in theory, affect the persistent inorganic mercury in the brain that she believes to be a contributing cause of autism.

and…

In concluding that petitioners have failed to establish that Colin’s TCVs caused his ASD, I emphasize that I have not applied a heightened evidentiary burden. I did not require scientific certainty, nor direct evidence of causation. Daubert requires that an opinion be supported by something more than subjective belief; it must be grounded in “the methods and procedures of science.” 509 U.S. at 590. There is no evidence that mercury has ever caused an ASD, only speculation that it might. At best, there is some evidence of an ongoing inflammatory process in ASD, but no indication that it is caused by mercury, and many indications that it is not.

This last paragraph has two points I want to highlight. The first is the citation of the standard of evidence used – as I said, less than scientific proof, but it must be based on something. The second is that Special Master Vowell acknowledges that there is no evidence “mercury has ever caused an ASD (autism spectrum disorder).” This is in contrast to the claim by some anti-vaccinationists that the VICP has admitted vaccines cause autism in some cases. They have not. They have only decided in certain cases that “compensation is appropriate” and in the cases often put forward, such as the Hannah Poling case, the child did not have autism but some other neurological disorder.

Conclusion

This most recent decision by the Autism Omnibus is a slam dunk – after an exhaustive review of the evidence, allowing both sides to present their best case, the three masters are unanimous in their strong opinion that there is no evidence linking thimerosal to autism. They trashed every claim and argument brought forward by the petitioners – the logic and evidence simply does not support their case.

Of course, the anti-vaccinationists cannot accept the unavoidable conclusion – the current evidence simply does not support their claim. So they predictably retreat to conspiracy-mongering. Read the comments to any anti-vaccine blog on this topic – there is the casual assumption that the masters (along with the CDC, AMA, FDA, AAP, and every science-blogger) are in the pockets of evil “big pharma”. They have their narrative, and they will not be distracted by anything so pesky as facts and evidence.

While this is a huge win, there is another case on the horizon that is the cause of some concern – Bruesewitz v. Wyeth. The Supreme Court has agreed to hear this case, which will test whether or not a family can sue a pharmaceutical company for an alleged vaccine injury and bypass the VICP. This case will be decided by the law – not science – and so I have no idea which way it will go. If the Supreme Court rules that people can bypass VICP this will undercut one of its primary functions, and the flood gates will open. Anti-vaccinationists could make it untenable for pharmaceutical companies to market vaccines.

While I applaud this follow up to the Autism Omnibus hearing, I hope it does not follow the pattern of Aliens and Star Trek and peak with the first sequel.

Note: Orac has also written a good review of this topic.

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