Sunday, October 11, 2009

Double Standards Applied to Autism Prevalence Data

With the recent dramatic change in estimated autism rates from 1 in 150 to 1 in 91 over just a two year period public health authorities, and Neurodiversity ideologues and pseudo skeptics have pulled out a number of arguments to deny, once again, that autism is rising, that there is a real increase in autism. The arguments used in denying any real increase in autism disorders over the past 2 years, are reruns of arguments used to deny increases in autism for the past 15 years. Very, very curiously, however, the same authorities, the same allegedly skeptical, scientific voices, denying autism increases also point to studies, particularly the Danish studies, using prevalence data reflecting decades of diagnoses from the early 1970's to 2000, a period encompassing drastic changes in diagnostic definition of autism disorders, heightened autism awareness, growth in autism services and increasing ability to diagnose autism.

The change in autism diagnostic definitions in the DSM III-R and DSM IV are trotted out once again 15 years later to deny the reality of autism rising. Increased social awareness is a favorite. And of course there has to be a blame the parents excuse: the alleged availability of autism services has resulted in parents seeking autism diagnoses for their children. Dr. Thomas Insel urged the world to be cautious because, after all, authorities are now better at diagnosing autism. It is not clear how the ability to diagnose autism increased by more than 50% over a two year period or what studies the good Doctor Insel relied on but after all he is the Chair of the IACC ... isn't he? But what are the implications of the unreliability of autism rate information for the vaccine autism studies which relied on such data over a longer period of time?

If all these factors diminish the reliability of a reported increase in autism disorders over a two year period, so long after the DSM III-R and DSM IV revisions of the diagnostic definitions of autism disorders, what are the implications for the vaccine autism studies that relied on increases in autism diagnoses after the removal, or the alleged removal, of thimerosal from vaccines? These studies were conducted using data that actually spanned the period prior to and after the period for which data was obtained. Can the prominent Danish studies still be used to assert that there is no correlation between thimerosal and autism?

The Madsen study (Pediatrics, September 2003) found that there was an increase in reported autism diagnoses after the removal of thimerosal from vaccines in Denmark in 1992. The authors also noted though that:

The increase in the incidence of autism from 1990 on may be attributable to more attention being drawn to the syndrome of autism and to a change in the diagnostic criteria from the ICD-8 tothe ICD-10 in 1994. Also, outpatient activities were included in the Danish Psychiatric Central Research Register in 1995 and because many patients with autism in former years have been treated as outpatients this may exaggerate the incidence rates, simply because a number of patients attending the child psychiatric treatment system before 1995 were recorded for the first time, and thereby counted as new cases in the incidence rates.

The above caution is not mentioned by those who claim that this study disproves a thimerosal autism correlation. Dr. Insel for example did not mention this caution when he appeared before Senator Harkin's subcommittee although he now frequently mentions such factors to downplay the recent reports of a more than 50% increase over a period of just 2 years. Dr. Offit speaks so often in support of vaccine safety that it is difficult to say that he NEVER mentions the caution expressed by the authors of the Madsen Danish study but I have never encountered it in his many high profile media appearances on the subject.

There are many other critical flaws in the studies cited by Insel, Offit and others as proving that there is no autism thimerosal connection, no autism vaccine, connection. They have been addressed at length elsewhere by Generation Rescue and other true skeptics. At this time what is terribly striking to me is the ease with which Insel and Offit and their follower's embrace wholeheartedly the studies which they claim support their no vaccine autism connection even though they suffer from the same factors they cite in denying a real autism increase, perhaps even more so. Conspiracy perhaps but the evidence is not sufficient in my humble opinion. Conflict of interest? Probably. Bad faith? Definitely.

Double standards and hypocrisy take on a serious twist in this story. The failure by Insel and Offit to properly inform parents of the risks associated with injection of potentially damaging substances into their children is justified by reliance on studies flawed by the same factors they point to in denying the existence of real increases in autism disorders.

Autism IS rising OR many of the vaccine autism studies of are of no value whatsoever. Those whose careers and livelihoods depend on denying environmental, including possible vaccine, contributors to autism are growing increasingly desperate but even they can not have it both ways when it comes to assessing autism prevalence.

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Richard said...

If autism rates are indeed going up as you say, doesn't that weaken the case that vaccines cause autism? Thimerosol has been removed from most vaccines, and, as a result of the vaccine/autism scare, vaccine use has dropped in the past several years. We should therefore be seeing a decrease in autism rates.

The recent NHS study seems to show that autism rates are the same throughout the population in each age group. That too is not consistent with a vaccine/autism connection, or with increasing autism rates.

It remains to be proved that that autism rate is increasing in the population. I do not understand why people think that doctors would want to hide the fact of increasing autism rates if it is indeed correct. It seems to me that they are honestly trying to find out if the rate is increasing, decreasing, or remaining stable.

Unknown said...


You didn't address the issue I raised. If a change in autism prevalance from 1 in 150 to 1 in 91, 15 years after the DSM changes were made, and covering only a 2 year period, do not reflect a real increase in autism then why should the Danish studies based on autism prevalence data covering 3 decades and straddling the DSM and ICD changes be reliable? Even the authors of the Madsen study pointed to that problem.

Do you have any comments on the issue raised?

Anonymous said...

So in your view, I must have tried to deny this latest development two and a half years in advance.

Anonymous said...

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