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Thursday, January 13, 2011

Autism,Vaccines, and the Wakefield Study: I. Reasons to Reject Wakefield's Report

Early in 2010, there was an excited reaction to the retraction by the British journal Lancet of an article published by Andrew Wakefield and a number of colleagues in 1998. That article had claimed that research evidence supported the hypothesis that vaccination for some childhood diseases played a causal role in the development of autism. Wakefield’s paper has been a major focus of the anti-vaccine movement and has encouraged parents to refuse vaccination of their children-- with some predictable results in terms of disease and even death of children.

Now in the early weeks of 2011, the British Medical Journal has published two articles by Brian Deer, the Times reporter whose investigation has done so much to clarify the errors in Wakefield’s work. The first of these articles, “How the case against the MMR vaccine was fixed”, appeared on Jan. 5. A second piece, “How the vaccine crisis was meant to make money”, was published Jan. 12.

Lancet's retraction of the Wakefield 1998 paper received attention from bloggers, journalists, scientists, and concerned parents, as we might expect. I’ll summarize some of the criticisms, as they are discussed by Brian Deer in the Jan. 5 article and elsewhere.

The majority of the critiques focus on the ethical errors in Wakefield’s work. Indeed, there were ethical errors by the carload. Wakefield failed to disclose his financial interests in vaccine protocols or in a relevant lawsuit where he was acting as a consultant; he procured blood samples from children whom he knew personally, thus making it awkward for the children or their parents to hesitate to consent to the procedure; he ordered unnecessary and intrusive tests for some children. All these ethical errors would be reasons for reprimands, for the withdrawal of job opportunities, for ordering Wakefield to attend an ethical training program. His withholding of financial disclosure would be good reason for a journal to refuse publication, to print a correction if the article was already published, or in some cases to retract the published material.

However, repellant as Wakefield’s ethical conduct may be, it is not in itself sufficient to support the decision that an article’s conclusion is wrong. A researcher might fail to document informed consent, might intimidate parents and children to get them to participate, and might secretly be on the salaried staff of a corporation with strong related business interests, but if his or her conduct of research, collection of data, and analysis of data were beyond criticism, the research itself could still be of value. Another researcher might follow all rules about informed consent and financial disclosure, but if he or she failed to do a good job in designing and carrying out a study, the conclusions drawn from that study would be worthless. Ethical errors raise questions about the researcher’s integrity in collecting and handling data, but are not necessarily evidence that the basic work has been done incorrectly. Compliance with ethical rules suggests that the researcher approaches his or her tasks with integrity, but adds no credibility to data or conclusions when it’s clear that these do not follow design guidelines. Journals refuse or retract papers when ethical errors are evident, but this is not because their action assures the publication of good material only; it’s because success or failure in publication are the major carrots and sticks available to enforce compliance with ethical rules.

I have seen very few comments about the design flaws of Wakefield’s retracted paper, so I will briefly list some. A major problem with the paper is the small number of children studied. Errors due to chance are much more likely to occur when a study involves twelve children than when it includes 120 children. Such errors might give the impression that an effect is much larger than it really is, but they could also make it appear that it is much smaller than it would appear to be with more data to consider. This is an especially important point in the light of other studies looking at many thousands of children and failing to reach the conclusions reported by Wakefield.

A second major problem has to do with Wakefield’s method of ascertaining what symptoms children showed, and at what times in their lives. Rather than using objective records like notes or videotapes dating from the children’s early years, Wakefield asked parents to recall events that had occurred eight years or more earlier. In taking this approach, he ignored the fact that human memory reconstructs past events rather than plucking them intact from some sort of bookcase of internal recordings. Previous and subsequent events help to determine how, or even if, reconstruction takes place. Memory research dating back almost a hundred years has shown that memories are influenced by expectation and motivation, and that repeated recall, rehearsal, discussion, and consideration of events change the way memories are experienced. These problems are real reasons why Wakefield’s study cannot be considered to provide evidence genuinely supportive of the conclusion drawn and much promulgated.

According to Deer’s investigation, however, there were far more serious problems than flaws in research design. Interviews Deer carried out with parents of children who participated in Wakefield’s study indicated that details reported about their children were not correct. (Because the number of children was so small, parents were able to recognize which case numbers actually represented their own children.) In one case, an American father stated that the child’s autistic symptoms occurred months earlier than the report stated, and in fact began before he received the vaccine. In other cases, there appeared to be no child in the report whose background as described by interviewed parents matched the reported histories. Several of the children had developmental delays and physical problems that were apparent before vaccination occurred. Of nine children described as having “regressive autism” (rather than autistic symptoms existing from early in life), three had in fact not even been diagnosed as autistic.

Deer’s investigation has made it clear that Wakefield’s work was not only sloppy, but involved apparently intentional distortions of the data. Why would Wakefield “fudge” his work? In a second post, I’ll discuss the reasons that Deer has shown.

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