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Views & Reviews Review of the Week

Trust me, I’m a scientist

BMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b3658 (Published 09 September 2009) Cite this as: BMJ 2009;339:b3658

Re: Close to agreement ?

With regard to the new NHS survey of adult autism mentioned by Sam
Lewis [1] I would think everyone ought to be disturbed at a study which
bases its national estimate for the rate of adult autism on just 19
potential cases detected. The 19 cases were identified in phase 2 of the
study using an ADOS inteview (Summary p. 13), but the results of an SCID
interview (Figure 3c p. 32) which should give a full DSM-IV diagnosis were
not made available. Dr Carol Stott, writing in the Age of Autism, posed
serious question about the methodology used - pointing out that there
does not appear to be a strong base for the use of ADOS in adults and that
the standardised scoring criteria were not used [2]. It is not clear that
we have fully diagnosed cases made by appropriately qualified people. This
is important since accurately profiling and diagnosing the 630 people who
took part in phase 2 - a huge task - would be essential to validity.

The 19 cases are from 7461 household which initially agreed to
cooperate, but the authors aver (p. 16)that they would have found a
further 53 cases among those not selected for phase 2. This may be in part
accounted for by the unsurprising steep drop out rate from the study -
cases which de-selected themselves - but selection for phase 2 was of
course based on psychiatric profiling in phase 1 (3.2.6 Sampling
procedures for phase 2 interviews p. 28), so they are apparently saying
that they got phase 1 wrong. But how do they know, and what basis does it
give for faith in their estimate?

All this is made more problematic by the publicity surrounding the
study. For example, the 1% rate of autism in adults which the authors
settled upon was already anticipated in pre-publicity citing a 1% rate in
children [3] and was linked to claims by NHS Information Centre that the
study cleared MMR of causing autism [4,5], despite the fact that the study
- which did not mention MMR - included young adults born in the years 1986
-1991 who would have had the vaccine anyway.

Other problems include:-

--The study made no attempt to locate lower continuum cases leaving
the existence of such cases in any numbers speculative

--Inclusion in the study was based on the 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 8.5 to 1)

--On table 3.6 (p.39) the 1% result is allocated a 95% confidence
interval, but it is hard to see how you can repeat what has not eachieved
in the first place

--A recent study also suppported by Autism Research Centre of the
University of Cambridge gave a rate of autism in school-children of 1.57%
[6]

[1] Brugha et al, Autism Spectrum Disorders in adults living in
households throughout England, Report from the Adult Psychiatric Morbidity
Survey 2007,
http://www.ic.nhs.uk/webfiles/publications/mental%20health/mental%20heal...

[2] Age of Autism, UK's NHS Report Suggests Autism Increase Due to
Oversight?, 25 September 2009, http://www.ageofautism.com/2009/09/uks-nhs-
report-suggests-autism-increase-due-to-oversight.html#more

[3] 'University of Leicester to lead audit of adults with autism'
Eurekalert 9 May 2008 http://www.eurekalert.org/pub_releases/2008-05/uol-
uol050908.php

[4] Sarah Boseley, 'Autism just as common in adults, so MMR jab is
off the hook', Guardian 22 September 2009,
http://www.guardian.co.uk/society/2009/sep/22/autism-rate-mmr-vaccine

[5] Michelle Roberts 'Autism rates back MMR jab safety' BBC News 22
September 2009, http://news.bbc.co.uk/1/hi/health/8268302.stm

[6] Baron-Cohen S, Scott FJ, Allison C, Williams J, Bolton P,
Matthews FE, Brayne C, 'Prevalence of autism-spectrum conditions: UK
school-based population study', Br J Psychiatry. 2009 Jun;194(6):500-9,
http://www.ncbi.nlm.nih.gov/pubmed/19478287

Competing interests:
Autistic son

Competing interests: No competing interests

01 October 2009
John Stone
Contributing editor: Age of Autism
London N22