By John Stone
Sometimes events across the pond seem connected. Just a few days ago the UK National Health Service’s Information Centre announced its new survey, which purportedly showed adult incidence of Autistic Spectrum Disorders running at the rate of 1 in 100 – according to them exactly the same rate as for schoolchildren, thus clearing MMR vaccine (or any other vaccine exposure for that matter) from being implicated in autism. Never mind that the rate was projected from a base of just 19 unconfirmed cases, or that the survey included young adults born between 1986 and 1991 who may have had MMR, or that the study had only high functioning and Asperger cases in it, or that the autism rate amongst schoolchildren in the UK runs at more like 1 in 64 - what an excellent opportunity for the US National Institute of Mental Health to concede that the autism rate for US children was also now 1 in 100, up from 1 in 150. There is now an official statistic they can cite that a rate of 1 in 100 for autism in both children and adults is perfectly normal, and nothing whatever to worry about.
To set the very curious British adult autism survey in context it is enlightening to return to the Eurekalert media announcement of May 2008 ‘University of Leicester to lead adult autism audit’ (HERE . We read:
“Professor Terry Brugha, Professor of Psychiatry in the Department of Health Sciences is spearheading the study in conjunction with a team of research experts including the the National Centre for Social Research (NatCen), Research Autism and Professor Simon Baron-Cohen of the Autism Research Centre. It will report in 2009.”
Interesting, first of all, to note that though it does not anticipate the result of the survey it does go on to cite a 1 in 100 autism rate figure for children in the UK:
“The number of children with autism is as high as 1 in 100 (according to studies by Prof Howard Meltzer of the University of Leicester and Prof. Baird's 2006 study). The new prevalence study now underway will give the first ever accurate picture of how many adults have the condition. “
This statement was highly misleading. Meltzer, who is a signatory to the new paper, seems to have been responsible for the 1 in 100 figure for children in UK National Statistics but this was not true of the Baird study which gave a rate of 1 in 86, while Baron-Cohen - who was not in the end a signatory - had already headed a study which when it was finally published furnished a childhood figure of 1 in 64 (HERE
But perhaps the most astonishing statement from the 2008 press release in retrospect is this: ‘The prevalence study will make use of new data collected in 2007 by NatCen and Professor Brugha’s team to record the number of adults with Asperger's syndrome and high functioning autism. There will also be an additional part to the study on the number of people with autism who have more complex needs and learning disabilities. The aim of the combined research will provide good epidemiological information in terms of prevalence and the characteristics and problems of this group.’
The new report, therefore, is based not on the full range of ASDs but solely on the data collected for the “Asperger syndrome and high functioning autism” by Prof Brugha in 2007; the “additional part” on “more complex needs and learning disabilities” has not been included at all, if it was ever conducted. On the other hand the report has been incorrectly published under a title which suggests that it is in fact a survey of all Autistic Spectrum Disorders “Autistic Spectrum Disorders in adults living in household throughout England” (HERE
) , and this was how it was announced to the media.
Other key questions arise:-
One is: why, if this report includes only people with Asperger’s Syndrome and high functioning autism - and only represents a proportion of ASDs - is the figure so high?
The diagnostic methodology has already been heavily criticised by Dr Carol Stott (HERE
Stott complained about the use of non-standard tests both in the initial phase 1 population screening – the specially created AQ-20 (Autism Quotient) - and in phase 2 the use of ADOS (Autism Diagnostic Observation Schedule), which is not well-established for adults, and which was not scored in a standard way. It also seems the more standard SCID (Structural Clinical Interview for DSM-IV Disorders) was carried out in phase 2 but the results not published. However, the single oddest feature is having screened 7,400 people in phase 1 and having retained 630 with the most likely psychiatric profiles for intensive screening in phase 2, they then hypothesised that apart from the 19 cases actually identified in phase 2 they had missed a further 53 in phase 1. This is puzzling: it would be rational to calculate you had missed some – particularly given drop-outs – but to calculate that you had missed nearly three-quarters puts the whole process in doubt, not least because the original purpose was that of charting unknown territory.
A second is: how can statistics compiled for only the segment of ASDs comprising Asperger Syndrome and high functioning autism be included in UK National Statistics as representative figures for all ASDs (at least those living in households)?
This seems to be an over-riding objection even before you consider methodology. An inscription at the head of the publication states: “This new set of statistics has not been formally assessed for compliance with the Code of Practice for Official Statistics. However, the Statistics Authority has agreed that, in view of the fact that the statistics are the product of secondary analysis of existing National Statistics, they can be designated as National Statistics. The producer body has confirmed that the new statistics are produced to the same standards as the existing ones.”
So, the Statistics Authority waived the necessity for compliance with its standards on the basis of assurances from the authors, or the institutions supporting them. On the other the fact that the statistics may derive in some way from National Statistics could not in itself ensure integrity.
--While the report did not refer to MMR or the vaccine/autism issue it was used by the NHS Information Centre to bolster MMR (Guardian
) it was not mentioned that study included young adults born in the years 1986 to 1991 who would have had MMR.
--Inclusion in the study was based on the willingness and ability of selected members of the public to answer questions on the telephone in the first phase and cooperation with a complex psychiatric assessment in the second phase. The results are self-selecting and unrepresentative.
--The 19 cases were unrepresentative of the population at large, including no one from an ethnic minority, and a low ratio of females to males (the usual ratio of males to females with ASD being about 4 to 1, but here 9 to 1).
--In an exercise in faux statistical precision, the study authors assign a “95% confidence interval” to their 1% estimate, but it is hard to see how you can repeat what has not been achieved in the first place.
Irrespective of cause it is tragic to see the great issue of autism prevalence betrayed in this way. What is actually shown here is that if the figure for adults provided by the survey was genuine it would still only be a relatively small fraction of cases in total: i.e. missing out low functioning ASDs, people living in institutions, all ethnic minority cases, perhaps half of females etc., but still coming up with the magic 1 in 100 – and the true rate of adult ASDs would be well in excess of 1 in 50, with all the most difficult cases left out and apparently still invisible. If we have learnt anything about adult autism cases it is that they are rather hard to find, so the 1 in 100 figure for what is apparently a small fraction is absurdly high and very poorly accounted. This study does not increase our knowledge: it just makes matters very much worse.
Little over three months ago Simon Baron-Cohen responded enigmatically to Anne Dachel of Age of Autism: “I agree we need a good prevalence study of ADULTS with autism spectrum conditions, and I haven't seen a study like this!”
Baron-Cohen obviously knew about this study which conspicuously does not now have his name on it as a co-author, despite this having been publicly announced in May 2008. It does, however, still have the imprimatur of Baron-Cohen’s Autism Research Centre. This whole episode has been immensely damaging and must corrode further the autism community’s trust in public institutions - eloquent testimony to what the British government really thinks about MMR and autism.
John Stone is UK Contributing Editor for Age of Autism