... The problems with the Verstraten study, the only epidemiological study that the CDC has done in the U.S. to examine the possible link between Thimerosal containing vaccines and neurodevelopmental disorders, are severe. It is such a badly designed and executed study that I can hardly do it justice in a blog post. I started working on a review of it about 6 weeks ago for my blog and I still have not finished.

In fact, it is currently the subject of a Senate investigation that may result in hearings on Capitol Hill.

I will try to do a quick review of my 'disdain' for it, as I actually think the harshness of your term might apply to my attitude in this case.

Verstraten started with a nice, simple study. He had medical records of about 180,000 kids in California, a good sized sample. He broke them up into four main groups, kids who received no Thimerosal, a little Thimerosal, a moderate amount, and a high amount. He checked to see if the amount of Thimerosal that they got, and when they got it (two months of age, six months of age, etc) corresponded to an increased risk for different types of neurodevelopmental disorders, and NDDs in general.

The study began in November of 1999 and was supposed to be finished in 4 months.

What he found was that the more Thimerosal a child got, the higher their chance of an NDD, with children who got the highest doses had a huge risk of having a disorder, more than 600% in one case. He also found that the age at which it was administered determined the type of disorder that a child would develop.

Verstraten sent an email to another CDC employee, Dr. Davis, and said that no matter what he tried, could not make the relationship go away.

In December the two men, and additional researchers at the CDC, began to change the parameters of the study. When you do this, you are supposed to document all the changes and justify why they are needed to properly answer the question you are asking. They did not.

The changes they began to make to the statistical analysis of the study are now described by the CDC as "improvements". How they could see some of these changes as improvements is unbelievable to me. Here are some of the changes:

They took the zero Thimerosal group, and tucked them into the low Thimerosal group. Now they only have three groups and in effect they have brought up the bottom, so the top does not seem as high.

That did not bring down the risk enough, so they decided to get rid of the no Thimerosal group all together, so now you are only comparing the low, middle and high groups, bring up the bottom further.

They got rid of a catch all group of NDDs so the study no longer addressed the question, 'does an increase Thimerosal increase the risk of a neurodevelopmental disorder'. Now it only looked at each disorder separately.

Still not dampening the signal enough, the decided to go into and change some of the actual medical records of the patients they were studying. The CDC reports that these were correcting errors in patient records, but will not offer any proof of this claim, saying instead that the data that would confirm their claim was 'lost'.

This brought the risk down, but still showed a link between Thimerosal and NDDs, so they then started dropping children from the study. They used about 20 different ICD9 codes to exclude any child from the study that had almost any birth complication or whose mother had almost any pregnancy complication. This included serious problems like premature birth and birth defects, but went all the way down to moms who took an antibiotic while pregnant. In effect this removes from the study many children who are likely to go on to develop NDDs.

This is fine to do in your study if you want, but it renders it almost completely useless for application to vaccine policy. This policy covers all U.S. children, and lots and lots of those children were subject to pregnancy and birth complications.

This study now no longer applies to my children as both of my pregnancies had complications.

At this point it is safe to say that this study no longer addressed the question of whether or not an increase in the dose of Thimerosal increases the chance of an NDD in American children. But the 'improvements' don't stop there.

Many more people are given a chance to make suggestions, the Simpsonwood meeting was held, comments are made that the study never should have been done in the first place, and the research is further bastardized.

A stop date was put in place so that children who were initially diagnosed with something like a speech delay, were then always considered to be speech delayed, even if they went on to be diagnosed with a more serious disorder like full blown autism. This is important as a large number of kids diagnosed with autism at ages 3 and 4 are diagnosed with some milder developmental delay at 18 months or two years of age. Doctors don't like giving the autism diagnosis early, and the state of California (where the study was done) won't even formally evaluate children for autism, or diagnose it before the age of 3.

I live in California. My son was evaluated at 2 and found to have 'speech delays' and offered early start services. To all involved in his treatment, he was autistic, but he did not become officially "Autistic" according to the state and his own records until age 3. Chandler would not have been considered Autistic for the purposes of the Verstraeten study.

My favorite 'improvement' was to add into the study children who were only a year or so old at the cut off date of the study. No child is diagnosed with autism, or indeed much of anything, this early. They all could have gone on to be diagnosed with a neurodevelopmental disorder but in the Verstraeten study, they are all considered healthy and unaffected by Thimerosal.

Even with all these shenanigans, they STILL could not completely get rid of the relationship between Thimerosal and NDDs. They then employed a tactic that served to make their own findings in the study irrelevant.

They split the whole group up into two, one large one from one HMO and one smaller group from another HMO (I think it was around 16,000). The small group was now too small to be of any statistical power. They used that group to say that the results in the first group could not be replicated in the second.

Then they bought another database from an HMO in New England, which was odd because they already owned dozens of them at the cost of millions of dollars in tax payer money. The HMO had failed and was in receivership due in part to poor record keeping on out of date computers. The HMO also used their own diagnostic system that didn't even implement ICD9 codes and the researchers used completely different parameters to study this database than they did in the first. They used this third group of only 12,000 or so patients, as yet another example of how they could not replicate the results of the first, large group, which they were now referring to as 'the screening study'.

The 4 month study took 4 years and, in my opinion, came out looking like something akin to Frankenstein's Monster.

This study does not offer a meaningful measure of anything and cannot be applied to any group that I can think of.

Add to this the fact Verstraten himself became an employee of Glaxo (currently being sued by parents of autistic children) half way through the study, which was not disclosed when the study was published, and it becomes easy to see why where the disdain comes from.

When asked to justify all the changes and publish the data so that the study could be confirmed and replicated, the CDC repeated the claim that the original data was 'lost'. A private contractor testified before congress that he had been ordered to destroy the data sets, "to insure patient confidentiality". This is a violation of federal law and is what sparked the congressional investigation currently underway.

It is practice in the scientific community that if a study can not be confirmed or replicated, that it should be withdrawn. Despite parent requests for such action, the CDC stands by this study and refuses to pull it.

As a parent who is looking at this issue as hard as I can, I am upset that the IOM, who should know better, keeps calling these studies 'well designed' and has used them to show that the case is closed on Thimerosal and autism.

Verstraeten himself says that the study is a 'neutral study' and does not find for or against Thimerosal in the implication that it is involved with NDDs.

In grad school, in order to pass statistics we had to take studies and break them down, justifying if and how they could be used for us to make treatment decisions. The Institute of medicine would have failed my 600 level stats courses.