Interverbal: Reviews of Autism Statements and Research
A critical look at science in the autism world
Tuesday, February 24, 2009
Mercury challenge misunderstandings: A guide especially for parents new to autism
Making decisions as a parent of a child diagnosed with autism can be tough. This doesn’t mean it has to be, just that it can be. One of the reasons it can be tough is that popular culture or the internet will bombard you with a variety of education plans, treatments, or therapies, many of which will claim to be scientifically proven or evidence based, but very few of which even come close.
One of the popular theories in the US, is that autism is caused by one or more forms of mercury. Where the mercury comes from depends on who you talk to, vaccines, dental fillings, fish, lights, computer screens, forest fires, and cremations have all been named as suspect. That may seem tricky enough, but the real question is in how children diagnosed with autism deal with the mercury.
Some sources claim that children diagnosed with autism are poor excretors of mercury. In other words for some reason they don’t get rid of the mercury their body accumulates (either in a fast or slow way) and that it poisons them and results in autism. For this group the advocates claim that mercury poisoning is difficult to assess. They may recommend assessing other biological factors as evidence. Or they may recommend a challenge (provoked) test for mercury.
Just to be clear, a provoked test is when a chelating agent is given to the patient and then the mercury test is administered. Some chelating agents bind to mercury and/or other heavy metals making it much more likely that they will be cleared from the body. This step is important for advocates of the poor excretor hypothesis, because they argue that the chelating agent captures mercury in the body. An increase between a non-provoked test and a provoked test is evidence of this according to certain parties. Or even without this non-provoked test, a provoked test that comes back in an elevated range can be evidence of this all by itself. However, others who advocate a mercury etiology of autism theory do not seem to put stock in the poor excretor theory. They advocate straightforward testing without a provoked test.
For a parent considering heavy metals testing a good first step is to decide which variant you believe in. These theories cannot both be true, they are exclusive. Children with autism are either poor excretors or they are not. And while some might try to be ingenious and claim that sometimes it is one and sometimes it is the other, I would ask the reader to decide whether this is truly a valid argument.
If a parent decides that the poor excretor hypothesis is unlikely, then there is no need for a provoked test.
If on the other hand a parent decides the poor excretor hypothesis is valid then a provoked test may seem reasonable. This is where my concerns begin.
My core concern is this; there is no mercury scale that was normalized with participants who were first given a provoking agent. This means that any of the provoked measurement will have to be compared to a scale established only with non-provoked samples. This is innately invalid, and yes, invalid is the right word here.
This is why: When one wants to establish a statistical scale, one must first create the conditions under which data will be collected. After data are collected a mean (average) is determined as is the standard deviation, which is simply a statistical way of determining how far away (in either direction) a given score is from the average. However, if you try to compare a given score taken under different conditions from how the scale was formed, it is no longer meaningful.
These data taken under different conditions were not included when the mean or standard deviations were calculated. For them there is neither mean nor standard deviation. The comparison is meaningless, and there is no way right to compensate for this problem at the moment. And while this may be a standard practice for many labs and practitioners, anyone who tells you these tests can be used to determine mercury poisoning is not using any recognized standard of science or statistics.
If you are a parent please be aware of these facts when you consider a provoked test.
Please everyone go read the Quackwatch article on urine metal testing. The article makes it crystal clear what the problems with this technique are. If you are a parent of a child diagnosed with autism who is considering or has done heavy metals testing you will especially find this article interesting.
Continuing to read up on the Insidevaccines group blog I decided to search their blog on my own interest which is Autism. I then found and read Helen Tucker’s “Bad Writing Can’t Save a Bad Study” published by Insidevaccines under a new title of “Vaccine Science??? Part II”. Having read Tucker’s piece, I read the article she reviewed, and then re-read Tuckers criticism. There are indeed a number of problems with Barlow et al. (2001), but what is remarkable, is that Tucker cannot seem to correctly identify a single one of them. Instead what Tucker offers us might be called a form of literary criticism.
“The entire paper was a convoluted description of how Barlow et al whittled the 679,942 children they said they studied in the abstract, to the 624 children they actually did study. The procedure was so complex that they used up most of the “Methods” section to explain it, and then resorted to a flow chart to present the final sample size as one of the results of the study.”
First, the entire paper is not a description of the ascertainment procedure, but instead contains all the appropriate components we should expect to see. Anyone who has thirty seconds can verify this. Second, saying the authors “used up” the methods section is silly. The methods section is as long as it needs to be. In fact in some research with complex procedures, the methods section is notably longer than what we find here. What is an actual concern in writing up research is a page limit for a given journal. This means authors must sometimes weigh what get the most attention. However, this is not the same thing as what Tucker describes.
Continuing, in the methods section the authors do describe a complex procedure. They are both scrupulous and clear in the description of ascertainment. This does not mean they lack the necessary parts. They have headings for (1) Study Sites, Sources of Data, and Identification and Classification of Cases, (2) Data on Immunization, (3) Statistical Analysis, and (4) Follow-up Study. Moreover, in the results section the authors do use a flow chart to present data on what they found in terms of unanalyzed data for seizures. Frankly, so what? Tucker’s criticism here has absolutely zero bearing on statistical problems or internal validity.
“They did not find any increased risk for nonfebrile seizures for either vaccine, compared to the control group (the non-recently-vaccinated). Any increased risks were then downplayed by comparing study seizure rates with “background” seizure rates obtained from the same HMO’s.”
No, they didn’t downplay increased risk. The authors are very clear here; there is no room for confusion and no reason to state that risks were downplayed. Here is what the authors actually said:
“Using the background rates of seizure in the Group Health Cooperative, we found that there were 5.6 and 25.0 additional febrile seizures per 100,000 children receiving DTP and MMR vaccines, respectively. Using published background rates of seizure from Kaiser Permanente of Northern California, we found that there were 8.9 and 34.2 additional febrile seizures per 100,000 children immunized with DTP and MMR vaccines, respectively.16 For these calculations, we used the estimated relative risks in Table 1 for each period of exposure, since these are the best estimates.”
“This paper is so muddled that it is tempting to suspect that it is muddled on purpose, as if to obscure fundamental flaws in its design. However, in the end, the flaws are too monumental to hide behind a fog.”
And yet Tucker never seems able to cogently present what flaws these might be.
“A relative risk study should have never been retroactive in the first place–it would have been easier and more scientifically valid to follow children who were either vaccinated or not vaccinated.”
Again, Tucker misses the boat. Relative risk studies can be, and are indeed done all the time using databases that were already in existence. That data have already been collected is in itself a frivolous criticism. The actual concern should be how well the given database controls for the 6 types of random and systematic statistical error and how well the authors collect those data. Building a case for how they collected data from the Vaccine Safety Database (VSD) is something the authors spend a fair amount of time doing in their methods section.
“The risk ratios are meaningless without knowing how many study and control children did not have seizures.”
Huh? Yes they did! The way data were collected there is a bias towards missing seizures that did not require hospitalization. However, there is no reason to think that severe seizures should bias the association, as the authors themselves note. Based on what the data indicate the authors can calculate how many children did not have seizure… at least severe enough to warrant hospitalization.
“The control group itself was poorly distinguished from the study group (recently vaccinated vs. non-recently-vaccinated), especially in a long-term study.”
From the article:
“The reference group at the time of the seizure was composed of children matched for age, calendar time, and HMO but who had not had a vaccination in the preceding 30 days.”
So, actually the difference was between groups was quite clear. As to the long-term follow up why would it be different if not explicitly stated? The authors noted at least one such explicit difference in their description of the follow-up study.
“Inclusion in and exclusions from the study were inadequately justified, yielding a sample that cannot be considered representative–of anything.”
The authors explicitly describe who was included and who was not. As to her comment about not representative, I have no idea what logical process she took to reach such a conclusion.
From the article:
“716 were confirmed to have had a first seizure during the study period. The primary reason for nonconfirmation was the identification of an earlier seizure.”
So, the author didn’t include kids who had an earlier seizure. In other words the study is representative of kids who didn’t already have seizures at the time of their DTP and MMR…. seems pretty fair to me.
“And perhaps the most glaring of all, the follow-up study excluded the most widely reported neurobehavioral diagnoses temporally associated with vaccines: non-infantile autism and pervasive developmental disorders. Murkiness on details can’t hide errors this egregious.”
The authors use the clinical manual of the ICD-9, this is appropriate as this is what the doctors used to report to the HMOs in the United States. And while some of the PDD criteria are used in current autism epidemiology via the ICD-10, the practical everyday reporting happens with the ICD-9-CM. However, most of the recent autism epidemiology in the West is done using the DSM-IV-TR, a completely different manual altogether.
Tucker’s criticism here is unfortunate, because at the year of publication there was little evidence that other PPDs and specifically PDD-NOS make up the majority of the PDDs in the epidemiology. In fact the good epidemiology such as Bertrand et al. (2001) and Chakrabarti & Fombonne (2001) used to help establish this fact would first appear in the same year as Barlow et al., but wouldn’t receive confirmation until Chakrabarti & Fombonne (2005) several years later.
In summary, Tucker indentifies no statistical problems, nor concerns with instrumentation, history, or selection bias. In fact Tucker identifies no threats to the validity of Barlow et al. I like reading science criticism and I like reading literary criticism, but I prefer a cleaner delineation between the two.
Further, some criticism needs to be directed at Insidevaccines. This may not have been their article, but they selected to reprint it in full with author permission, but without comment and give it blog-time on their site. Again they are the ones promoting it and so can be held in part accountable for its lack of quality. That one or more of them didn’t write it is irrelevant; it is re-printed in full on their blog, this is what matters.
For a blog that gets promoted as a model of good science I have thus far been very disappointed by Insidevaccinesm both in the current post and in the one I reviewed the other day. More time will be needed to see if some of their other “heavy science” articles are better than this. And while forming a group that looks at vaccine issues from a variety of viewpoints might be a good thing, sacrificing science in the process is not. References
Bertrand, J., Mars, A., Boyle, C., Bove, F., Yeargin-Allsop, M., & Decoufle, P.(2001). Pediatrics, 108, 1155-161.
Chakrabarti, S., & Fombonne, E. (2001). Pervasive developmental disorders in preschool children. Journal of the American Medical Association, 285,3093-3099.
Chakrabarti, S., Fombonne, E., (2005). Pervasive developmental disorders in preschool children: confirmation of high prevalence. American Journal ofPsychiatry, 162(6), 1133-1141.
“Inside Vaccines” is an interesting blog that offers views from a variety of standpoints concerning vaccines issues. Like many group blogs the articles differ massively in quality. This blog is seen by some as a model of good debate and scientific advocacy and is promoted by certain parties as such. For my part, I think someone really ought to systematically review “Inside Vaccines” and see how well this claim holds up to scrutiny. Some of the articles seem a bit creative in their interpretation of epidemiology.
Relative to our topic today, I would like to review “Vaccines? Safe. Parents? Dangerous”. I cannot determine whether this post has one or many authors. This is of no concern. What is a concern is the attitude toward science promoted within the posting. I will quote large chunks of the post and my reply to them below.
“Lately I’ve been noticing an increasing number of journal articles, blog articles and opinion pieces on a terrible problem: Parents have questions about vaccines.”
This is not a problem. It is reasonable and perhaps necessary to inspect both current health issues and older science from time to time. Scouring for merit and questioning are the tools by which correction of science may occur. However, what is a problem is the promotion of pseudo or anti-science under the guise of self-correction. For many of us, this is our concern, not the legitimate questioning of science.
“You would have to look far and wide to find anyone who thinks that these questions are valid and should be taken seriously.”
Perhaps the author(s) of the post have done neither.
“Common explanations are:1) It is all about the parents who think they are really smart.2) It is all about the parents who are very stupid and read stuff on the Internet.3) It is all about the bad stuff on the Internet which is deceiving the parents who aren’t very smart and who think they are smarter than doctors. And infinite variations on this theme, which is really one argument…and the real argument is (drum roll)…vaccines are perfect and parents are the problem.”
And do we see this among the science based bloggers or scientists that are well known? Or is this a reference to Mr. Haggen-Daas, your grumpy and opinionated old neighbor down the street. If you mean the former, I think I am going to have to ask for quotes or call straw argument at this point.
“Oddly, however, the number of parents with questions seems to be increasing. Perhaps the vaccine defenders need to reconsider their approach.”
Yes, the numbers do seem to be going up. That is okay, questioning is not the problem. I don’t think science has anything to fear from questions. On the other hand, there is a big problem when information is dressed up as science, but is actually.... not science.
Let me be direct here. I do not care if people question vaccines. For that matter I do not care if the majority people hear a variety of argument and adopt a very different view from the one I hold. What I do care about is the consistent application of science; this is a concern based on logic. What I also care about is that people have a right to be given accurate even if emotionally hurtful information; this is a concern based on ethics.
“Here are some suggestions, kindly meant, from an admirer of their efforts. These guys have put a lot of sweat equity into defending vaccines and they ought to be getting better results”
Why so? People exposed to our arguments will still make up their own minds. Our efforts do not somehow intrinsically merit the greater popularity. Of actual concern to me and those like me is how science is used and promoted.
“One argument which comes up over and over again is herd immunity.”
This actually seems to be a talking point of the vaccine etiology of harm theory advocates, not of those bloggers who hold a similar view to myself. I am not saying that it is never used, but that it is rare. In fact, I would argue that herd immunity is one of the favored whipping-boys of those who advocate a vaccine etiology of harm theory and that mention of it is disproportionate. I think a great little “study” would be to look at the Autism Hub and look at the Age of Autism blog and see how many times “herd immunity” pops up and who uses it. The results could be quite interesting no matter what they find.
“In addition to the defenders acting as though all vaccines are identical in their efficacy, safety and relevance, they also tend to act as though all vaccine questioners are identical. Anyone who has a question, is, in the defenders view, anti-vaccine.”
You treat us as monolithic; moreover you offer no quotes or references for such an opinion. Your comment here should not be mistaken as being logically sound.
“And people who are anti-vaccine are bad people. As a result the defenders respond with sarcasm, rudeness and repetition.””
There are indeed people who are largely or wholly anti-vaccine. They are not the majority, but they are out there. I do not think of them as bad people. I do not think of them as fools. I understand too, that all people are going to occasionally land on a stupid, illogical, or anti-scientific comment, perhaps in spite of their general inclinations. To counter-act this, I select to make my own arguments which attack and correct the errors that I see. Some people may be hurt by the information I provide or by the questions I pose. Even so, I am obligated to speak up if I see a problem, this is the same for anyone and everyone. I would cite failure to do so, as a form of unethical behavior.
“Some parents who raise concerns are just raising concerns. They haven’t gone over to the dark side. But with enough rudeness and sarcasm from the vaccine defenders they will definitely be moving in that direction.”
They may, but that is their choice. Do not misplace their decision on others. Please note, I am advocating neither the appropriateness of rudeness nor sarcasm, but only that people can select a course based on what they value. In my view however, this course of action is particularly illogical. It is not their emotions or desire to be treated with respect that is illogical, but their decision based on their emotions. Most of us will have had a teacher at some point in our lives we could not stand. Does this somehow make what they taught us untrue? Do we now have license to reject fact, because we were mistreated?
“Which leads me to the next problem. It is not, absolutely not, all about autism and vaccines.”
True, but for many of us coming from many views, this is indeed the main bone in contention.
“Try being polite and sympathetic. I know this is tough and doesn’t come naturally, but it is absolutely essential if the vaccine defenders want to get anywhere in this battle.”
I understand polite, but what do you mean by sympathetic? Do you mean that I should:
A) Consider the author’s view and try to understand their feelings? B) Accept (or at least avoid questioning) certain accounts that my inclination towards science has taught me to question? C) Both A and B D) None of the above
There are two choices above that I am going to reject as being unethical.
“The articles on this blog provide good models for a sympathetic, thoughtful and scientifically oriented approach.”
I would be interested to know which of the above your particular post models.
“Vaccine defenders need to deal with the science. Saying that the science is all on the vaccine side, without actually presenting said science is a hollow argument.”
Here we stumble upon some agreement.
“A sub-point on science: the scandals about faked science in medical journals are undermining people’s faith in doctors and science in general. If Merck did some bad stuff with Vioxx, is it unreasonable to have questions about their trustworthiness when it comes to Gardasil? The defenders need to be able to explain why vaccines are an exception to dirty dealing from the pharmaceutical companies. I’m wondering about this one myself and look forward to seeing what the vaccine defenders come up with.”
It has been tackled before…. multiple times in fact. The blogosphere is a big place, no doubt explaining why you missed it. The answer is this; vaccines should not be a special case, but the general case. Because companies are run by imperfect beings they occasionally deal dishonestly. This is a very good reason to be careful, scientifically conservative, to expect replication, and to revisit old issues. This is no excuse at all to offer a carte blanche dismissal of well designed science.... no matter who funded it.
“Calling people anti-vaccine isn’t actually an argument.”
Exactly, it is a description that may or may not be accurate.
“Selective and delayed vaccinators are potential allies who will fight for vaccines, but currently the vaccine defenders want nothing to do with them. Some of these parents are quite knowledgeable and have done extensive research into vaccines. They know more of the science than the defenders, frankly.”
If you are going to offer an argument, then offer an argument please.
“But defenders want nothing to do with them, because in a black and white world you are either with us or against us and there is no middle ground. Pushing away allies is dumb.”
If we both advocate for certain vaccines then we are already allied on this particular issue, right? If this is the goal then we simply press on. But if what you mean is actually mutually coordinated advocacy then I would want to know to what extent you will be simultaneously advocating your other views that I do not agree with. And to what extent will I be creating a platform for you to advocate such views. Also, I would want to know whether I am expected to put aside our disagreements, because of our coordinated advocacy. Based on this cost-benefit analysis I may or may not see our collaboration as the best option. Perhaps too, the people who want nothing to do with the selective and delayed vaccinators see a proposed collaboration as creating more problems than it solves. I think mutually coordinated advocacy is possible, but a number of issues would have to be resolved first.
“Now comes a truly tough one: The vaccine defenders should be strongly, passionately, in favor of a philosophical exemption to vaccines.”
I am in favor of such, but not for scientific or practical reasons. My agreement here is based on an ethical reason, the right to self-determine, in this case via proxy. My agreement here is neither strong nor passionate. Instead it is tentative, quite possibly to be removed. The post author(s) predict that this would actually increase the vaccine rates. I see zero evidence for that. It may be true, but then maybe not. If not and certain vaccine rates plummet, then one or more very serious health issues could arise. If so, then I would argue that a significant amount of parents have failed to be a reasonable proxy for their child in this regard, and that philosophical vaccine exemptions should be removed.
“Now, listen carefully, because this is the most important point of all. Defenders should stop denying vaccine damage.”
Illness or injury from vaccination happens. A new or newly modified vaccine may not be as safe as initial tests suggest. A batch may go bad. An individual may have a unique or rare reaction. Although there may very well be disagreements about rates of injury, that fact that injury itself occurs is not a point of contention among any players in the debate.
“When a parent testifies that their child was damaged by a vaccine they should fall all over themselves to acknowledge what happened, to agree that vaccines can, indeed cause injuries, to encourage the parent to report what happened to VAERS, to sympathize if they say the doctor denied the incident and refused to report it.”
Wouldn’t this depend on the case? If you said that your child regressed a month after her MMR and now meets criteria for Autistic Disorder, I am probably going to question whether there is a connection. These events are not that close in proximity. I have reason to question and/ or to suggest that you question your assumptions. If I offer nothing but sympathy, then I am probably helping you feel better, but I am also engaging in enabling behavior towards anti-science. It seems to me that the author(s) try to assume the mantle of science, but reject it when expedient.
“They even see, as I recently did, a vaccine defender proclaiming gleefully that the VAERS system is useless and cannot be used as a source of information about the risks of vaccines. What sort of message are vaccine defenders sending out to the public? Clear enough, unfortunately.”
The VAERS does a good job doing what it was designed to do. Being a rapid and ongoing system to monitor and hopefully detect problems with vaccines. It is an imperfect system, but it does the job it was designed for. When it is forced fit into epidemiology then the VAERS has very little utility. It is a database that controls for none of the 6 types of statistical threats. It has been used this way by a variety of people working on a variety of issues. The VAERS data are un-refereed and uncontrolled. Don’t confuse monitoring and formal epidemiology, and don't twist a data set into something it is not.
“On the same note, a good study comparing vaccinated and unvaccinated populations will obviously prove that vaccines are safe, right? So why don’t the vaccine defenders fight for such a study? Vaccines make children healthier and the evidence should be easy enough to find. Yes?”
I have no problem with additional research. However, since this is what you are calling for, this is your burden. “Are they really fighting to defend vaccines or are they just out there to tell everyone how smart they are? Some of us are wondering.”
Using an ad hominem to close I see.
Well, thank you for the advice. I would like to reciprocate your gesture and offer some advice too.
1) Do not claim to be an admirer of our efforts and then slander us with ad hominem arguments, we will note the inconsistency.
2) Do not claim your blog as a model of science then abandon it when an emotive issue arises, we will note that your work is not as scientifically oriented as you claim.
3) Do not claim your advice is kindly meant and then deploy arguments that are really quite snotty. We will question your work's intellectual integrity.
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