A Positive Association found between Autism Prevalence and Childhood Vaccination uptake across the U.S. Population (Original Taylor number = 51, second Taylor number = 4, current Taylor number = 6)
Correct citation: Delong G., A positive association found between autism prevalence and childhood vaccination uptake across the U.S. population. J Toxicol Environ Health A. 2011;74(14):903-16. doi: 10.1080/15287394.2011.573736.
Author affiliation: The author is not a medical researcher or an autism expert. She earned her PhD in Finance and International Business, and currently is an Associate Professor of Economics and Finance at the Zicklin School of Business, Baruch College, City University of New York. At the time the paper was published, she was a member of the executive board of SAFEMINDS, an acronym for Sensible Action For Ending Mercury Induced Neurological Disorders, an anti-vaccine group devoted to the discredited notion that a preservative in some vaccines was causal in autism. Professor DeLong is no longer associated with SAFEMINDS at the board level. DeLong once described herself as "a parent of two girls with autism. Starting in May 2005, her family began biomedical interventions to treat the girls’ illness. Both girls have benefited greatly from supplements, diet, chelation, and hyperbaric oxygen therapy.... She has attended rallies in Washington, DC to promote safer vaccines and spoken against adding vaccines to New Jersey’s mandated schedule at a public hearing"
Nature of journal: Journal of Toxicology and Environmental Health, Part A has an Impact Factor of 1.733, and a track record of publishing highly questionable papers on the connection between vaccines and autism, including two papers by the Geiers.
Methods: There are many egregious flaws in this paper. To begin with, the introduction. DeLong misrepresents the scientific consensus on the possibility that receipt of vaccines is somehow connected to autism (the scientific consensus is that there is no connection). The sources she cites for this connection include the
Then the use of educational data (The Individuals with Disabilities Education Act (IDEA)) as source data
Under IDEA, every school is required to provide data on children who have an Individual Education Plan (IEP), including the students’ primary classification. As Liz Ditz pointed out, IDEA classifications are not medical diagnoses. A child with a diagnosis of autism under IDEA may or may not really have autism. Also, children with an IDEA classification of SLI are most commonly children with problems in fluency, articulation, or voice, not autism. Examples include apraxia and aphasias, voice disorders, stuttering, and language-based learning disabilities.
It had been clear for more than 5 years before DeLong published her paper that IDEA or educational data is unreliable as a source of autism prevalence. That the author blithely used such data is a very serious condemnation of the paper.
Then there is the issue of subsuming Specific Language Impairment (SLI) with Autism, as the author does in this paper. Dorothy Bishop is a professor at Oxford University; her whole career has been spent researching SLI. While she agrees that there may be some overlap between SLI and autism,
nobody would ever dream of treating them as interchangeable. It has never been suggested that SLI is caused by vaccination; it is highly heritable and typically involves very slow onset of language from the earliest stages. It is also considerably more common than autism.
Another fatal flaw is that the author rests her argument on the ecological fallacy:
The ecological fallacy occurs when you make conclusions about individuals based only on analyses of group data. For instance, assume that you measured the math scores of a particular classroom and found that they had the highest average score in the district. Later (probably at the mall) you run into one of the kids from that class and you think to yourself "she must be a math whiz." Aha! Fallacy! Just because she comes from the class with the highest average doesn't mean that she is automatically a high-scorer in math. She could be the lowest math scorer in a class that otherwise consists of math geniuses!"
Further commentary on this fatally flawed paper
- http://leftbrainrightbrain.co.uk/2011/06/11/speech-impairment-and-autism-inseparable/"The "vaccination rate" (they have a very odd definition) goes up dramatically in the first two years of the study. The "autism+SLI rate" does not. If there were a real association between the two, it would be clear in those first columns of data.
- http://neuroskeptic.blogspot.com/2011/05/vaccines-cause-autism-until-you-look-at.html "My conclusion is that this dataset shows no evidence of any association. The author nonetheless found one. How? By doing some statistical wizardry."
- http://biologyfiles.fieldofscience.com/2011/06/gayle-delong-safeminds-board-member-and.html "The acceptance and publication of this paper appear to have been careless to an extreme. I'd like to know who the reviewers were."
Remember that the compiler of this list of papers made the following assertion:
Here we provide for the reader research that demonstrates the link between vaccines and autism, and the mechanisms by which vaccines can cause autism.
Does this paper effectively demonstrate a link between vaccines and autism? No.
Does this paper demonstrate the mechanism(s) by which vaccines can cause autism? No.