Thursday, January 15, 2009

Autism in California: The MIND's new epidemiology

ResearchBlogging.org
The MIND's recently published autism epidemiology (Hertz-Picciotto & Delwiche, 2009) has been widely publicized (press release is here, typical media story is here), with the upshot that large increases in reported rates of autism are real rather than apparent and should be studied as such.

Bloggers have taken on several aspects of the MIND's new autism epidemiology (here, here, here, here, with more and a summary here) as well as discrepancies between the paper itself and how it has been promoted. I'm going to add just a few more points to consider.

This isn't the MIND's first crack at epidemiology. Their previous highly publicized but unrefereed report, described as "A Comprehensive Pilot Study," was shown, in a refereed paper (Gernsbacher et al., 2005), to suffer from "unwarranted conclusions" about the effect of changes in how autism is diagnosed on reported rates of autism.

So what's new, this time around? Hertz-Picciotto and Delwiche use census data to account for migration into California, so as to generate what they call incidence (rather than prevalence) figures. Also, they've included individuals identified as autistic, for the purpose of receiving services, before age three.

But the basis for the MIND's new epidemiology remains the same: the California DDS data. Turning DDS figures into incidence data doesn't alter the problem that DDS-type administrative numbers should not be used as epidemiology. The pitfalls of using service-based numbers have been explored formally in the literature (e.g., Laidler, 2005; Gernsbacher et al., 2005) and expressed less formally by an NIH official:

"I'll call a kid a zebra if it will get him the educational services I think he needs."
Hertz-Picciotto and Delwiche's inclusion of children identified in service records as autistic before age 3 raises the problem that early diagnosis of autism may be very unstable. In Turner and Stone (2007), only 53% of children diagnosed autistic at an average age of 29 months kept their autism diagnosis at an average age of 53 months. Diagnostic instability was related to earliness of diagnosis (the earlier the diagnosis, the less stable it was) but unrelated to interventions received.

Like Hertz-Picciotto and Delwiche's conclusions about changes in diagnostic criteria (pulled from an unrelated Finnish prevalence study; Kielinen et al., 2000), their conclusions about effect of including other autistic spectrum diagnoses (Asperger's and PDD-NOS, which the authors presume are "milder cases") do not arise from the incidence data they report. Instead, figures were taken from an earlier paper involving a specific (much smaller and narrower) sample of children recruited to study environmental causes of autism (Hertz-Picciotto et al., 2006).

According to Hertz-Picciotto and Delwiche, their study involves children with the specific diagnosis of autism only. The authors refer to "an International Classification of Diseases (ICD) code of 299.0 (autistic disorder)" (except of course this is a DSM-IV, not ICD, code and category), while assuming that children diagnosed with other autistic spectrum diagnoses do not meet ADI-R or ADOS cut-offs for autism or ASD (ADI-R has autism cut-offs only). This, the premise of the authors' analysis re what they presume to be "milder cases," doesn't stand up well to scrutiny.

For example, in Baird et al. (2006), 69% of children with non-autism autistic spectrum diagnoses met autism criteria on the ADI-R. This doesn't count Asperger children, who were lumped in with autistic children, virtually all (98%) meeting ADI-R autism criteria. In work I'm involved in, virtually all Asperger individuals (as virtually all autistics) meet all ADI-R and ADOS cut-offs for autism.

Also, in using the ADOS (which has, more recently, been revised again) and ADI-R, as well as clinical experience, Baird et al. (2006) produced a range of prevalence figures for children aged 9-10, from ~25/10,000 to ~116/10,000. That's a 4.6-fold discrepancy in the same sample at the same time with the same instruments and the same group of diagnosing clinicians.

Maybe there are other ways of exploring whether children receiving DDS autism services in the past are similar to children receiving these services more recently. In their unrefereed 2002 report, the MIND compared subsamples of children born from 1983 to 1985 with children born from 1993 to 1995. In the earlier subsample, 61% were judged to be in the range of intellectual disability, whereas in the later subsample, 27% were--a discrepancy noted by Gernsbacher et al. (2005).

More data about the entire population receiving DDS autism services are available. In a 1999 DDS report, graphed data show that whereas in 1987, ~84% of those receiving DDS autism services were judged to be in the range of intellectual disability, by 1998 that figure was 58%. A further look at DDS quarterly reports shows that by the beginning of 2002, that figure was 42%, and by the end of 2007 it was 33%. Between 1987 and 2007, the proportion of individuals receiving DDS autism services and scoring in the severe and profound ranges of intellectual disability dropped from ~36% to ~6%.

So--there are a few more reasons to question Hertz-Picciotto and Delwiche's conclusions about the effect of differences in how autism is defined and diagnosed. Also, there are many reasons to question the whole enterprise of trotting out DDS numbers yet again and pretending that, with enough distracting decorations stuck on, they in fact are epidemiology. After all, Hertz-Picciotto and Delwiche are denying the existence of older autistics, and they are doing this by using poor quality data dressed up in definitive conclusions. I would be much more cautious than Dr Hertz-Picciotto and her university have been, in going out in public wearing the MIND's new epidemiology.


Reference:

Irva Hertz-Picciotto, Lora Delwiche (2009). The Rise in Autism and the Role of Age at Diagnosis Epidemiology, 20 (1), 84-90 DOI: 10.1097/EDE.0b013e3181902d15

21 comments:

Jannalou said...

I'm reading Unstrange Minds (Grinker) right now, and when I read about the MIND paper, I did a double-take, because I distinctly remember reading about prevalence, incidence, and California's numbers in particular, not two weeks ago. There's something confused about their numbers, to be sure.

Michelle Dawson said...

In response to Janna, there's a review of Dr Grinker's book here. It's written by Dr Gernsbacher and published in Nature Medicine.

RAJ said...

There was another rise in the incidence of autism that occured within a decade of Kanner’s paper published in 1943 that defined ‘autism’. In 1965 Kanner explained the phenomena which had disappeared by the mid 1960’s. Kanner explained this long forgotten autism ‘pandemic’ as one not of broading diagnostic criteria but one of gross misdiagnosis. His explanation is relevant to the current disussion of the myth of a global autism pandemic.

http://neurodiversity.com/library_kanner_1965.html

Kanner wrote :
“Moreover, it became a habit to dilute the original concept of infantile autism by diagnosing it in many disparate conditions which show one or another isolated symptoms found as a part feature of the overall syndrome. Almost overnight, the country seemed to be populated by a multitude of autistic children, and somehow this trend became noticeable overseas as well”.

The trend to overdiagnosis of autism can be traced to various editions of the APA’s DSM’s starting in 1980:

http://www.unstrange.com/dsm1.html

In DSM-III (1980) Kanner’s definition ‘Pervasive lack of responsiveness to other people (autism)’ was required to qualify for an ‘Autism Spectrum Disorder’.

In the revised DSM-III-R (1987) Kanner’s definition was relegated to just one of five isolated symptoms in the social domain and was not required to qualify for an ASD diagnosis. A field trial comparing DSM-III to DSM-III-R criteria found that ‘autism was being overdiagnosed:

http://www.ncbi.nlm.nih.gov/pubmed/1483972

When DSM-IV (1994) was introduced, the subsequent years produced an astounding seemingly worldwide autism pandemic with prevelance rates sky rocketing from 4 to 6 cases per 10000 to 1 per 150. DSM-IV completly removed Kanner’s definition and replaced it with the vague, ambigous and subjective:

‘Qualitative impairment in social interaction’

This has resulted in conferring an ASD diagnosis in children who would never have qualified for an ‘autism’ diagnosis using Kanner’s defnition in DSM editions prior to 1987, including mentally retarded children with ‘autistic-type’ behaviors and Romanian orphans subjected to extreme social isolation and were adopted into well-functioning English families who also meet diagnostic criteria for an ASD. We now have the same phenoma of what Kanner described in 1965:

“Almost overnight, the country seemed to be populated by a multitude of autistic children”

What would Kanner have called the APA’s committee on Autism and the PDD’s who were responsible for the diagnostic criteria published in DSM-IV in 1994? More than likely he would have described the framers of DSM-IV as ‘acrobatic jumpers who go in for the summary adoption of diagnostic cliches and have found a new bandwagon, ‘Autism Spectrum Disorders”. Had the framers of DSM-IV used a more accurate and descriptive label such as neurodevelopmental disorder spectrum and reserved Kanner’s definition for the small subgroup who actually met diagnostic criteria for Kanner’s definition, the entire myth of a global autism pandemic could have been avoided.


“(1) Diagnostic criteria have changed over some part of the period during which increases have been observed. The diagnostic criteria for autistic disorder were broadened over time”.

Broadening of diagnostic criteria has been invoked to explain the appearance of a global autism pandemic. ‘Broadening’ implies a base where autism is narrowly defined and broadening the criteria will be more inclusive for the larger group of children who were in trouble developmentally but defied categorization. In fact, ‘broadening of diagnostic criteria’ is linguistic acrobatics. The narrow definition of ‘autism’ was not broadened, it was completly abandoned in 1994 with the removal of Kanner’s criteria.

All current 'Gold Standard' diagnostic schemes are based on DSM-IV incluidng ICD-10 and ADOS-G Auti-R ARI-R etc.

DSM-IV contains a checklist of 12 symptoms and if enough of these isolated symptoms are checked off, the patient will qualify for an ASD diagnosis using Gold Standard diagnostic tools such as ARI-I and ADOS-G. Not one of the twelve symptoms are specific to autism.

Michelle Dawson said...

According to RAJ (who has posted this kind of comment, with few variations, in numerous places),
there should be no consistent findings in the autism literature across time. But this is not the case.

Possibly, many clinicians using the current major diagnostic instruments for research purposes (e.g., for cognitive science or neuroscience) are aware their limitations, understand the problem of phenocopies, and so on.

This doesn't mean that the current gold-standard diagnostic instruments (ADI-R, ADOS) do not have major problems. The recent revision of the ADOS (and a recent, preliminary attempt to recalibrate it) is evidence that these instruments are works in progress.

Also, the need for finer-grained observation in identifying individuals likely to be autistic has not only been stated, it has been productively investigated (Mottron et al., 2007), with the findings recently replicated (Ozonoff et al., 2008).

RAJ said...

"According to RAJ (who has posted this kind of comment, with few variations, in numerous places),
there should be no consistent findings in the autism literature across time. But this is not the case".

Michelle, here is the challenge..Name one isolated symptom listed in DMS-IV that is specific to 'Autism'.

Here is paragraph 3 of DSM-IV diagnotic criteria for Autistic Disorder:

"Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction, (2) language as used in social communication, or (3) symbolic or imaginative play".

Ironically, delays or abnormal functioning in social interaction is not even a requirement to qualify for a diagnosis of Autistic Disorder under all diagnostic schemes currently in place.

All social/communication difficulties are not the exclusive domain of 'ASD's.

In fact the triad of impairments believed to be the defining feature(s) of ASD's occur in adult stroke patients, including impairment on social reciprocity:

http://www.ncbi.nlm.nih.gov/pubmed/9745234

"Ratings for the personality items were summed to create an aggregate score. Analysis of these scores revealed both LHD and RHD patients to have lower (i.e., more negative) mean scores than NHD patients, suggesting that stroke patients as a whole were seen as socially impaired".

A priority for autism research would be to apply ADOS-G or any other Gold Standard diagnostic scheme to a representative group of inpatient adult stroke patients which should validate (or not) the entire concept of the definition of 'social impairment'.

Again, name one of the twelve isolated symptoms listed in DSM-IV that you consider to be spcific to 'autism'.

I have no objection to the concept of diluting the diagnostic criteria for 'autism' if it means issuing a passport to special education and behavioral interventions for a large group of children with development delays who prior to 1994 were on their own and denied any help.

The largest group in the increase of ASD's is the designation of PDD/NOS which Johnny Madsen has accurately described as being defined by what it is not -'autism'.

It is this group diagnosed with PDD/NOS that have been demonstrated to have the best chance for losing teir diagnosis and having a normal outcome:

http://www.ncbi.nlm.nih.gov/pubmed/19009353?

"Although Autism Spectrum Disorders (ASD) are generally assumed to be lifelong, we review evidence that between 3% and 25% of children reportedly lose their ASD diagnosis and enter the normal range of cognitive, adaptive and social skills. Predictors of recovery include relatively high intelligence, receptive language, verbal and motor imitation, and motor development, but not overall symptom severity. Earlier age of diagnosis and treatment, and a diagnosis of Pervasive Developmental Disorder-Not Otherwise Specified are also favorable signs".

Michelle Dawson said...

As I wrote above, according to RAJ, there should be no replicated findings in the autism literature across time or for that matter across different research groups. This is not the case.

See, e.g., Lockyer and Rutter (1970), Rumsey and Hamburger (1988), Shah and Frith (1993), and Caron et al. (2006).

Re instability of diagnosis, see Turner and Stone (2007), mentioned in the original post.

Alyric said...

"only 53% of children diagnosed autistic at an average age of 29 months kept their autism diagnosis at an average age of 53 months."

Now that's highly significant. Jenny McCarthy's book describes a lot of 'cured' kids who were diagnosed at 2 and undiagnosed at 4.

Jannalou said...

Thanks for the link, Michelle. I'll be posting my own impressions of Grinker's book at some point in the future.

MIND's numbers are definitely suspect.

RAJ said...

"As I wrote above, according to RAJ, there should be no replicated findings in the autism literature across time or for that matter across different research groups. This is not the case".

Ther is no REPLICATED findings with respect to epedemiology or prevelance rates since 1994. The trend is always on an ever increasing trajectory from 4 - 6 per 10,000 to 1 in 150 the most current assessment.

You also refuse to respond to the original question.. Name one of the twelve isolated symptoms published in DSM-IV, ICD-10 or any of the expanded number of isolated symptoms that are contained in any of the Gold Standard diagnostic tools (ADOS-G, ARI. ARI-R AUTI-R) that are specific to 'autism'. You can't because none exist.

Maybe you can explain howe these Gold Standard diagnostic tools can confer an ASD diagnosis on such diverse groups as Romanian orphans who were institutionalized at birth and suffered extreme emotional deprivation and also met diganostic criteria for an ASD using Gold Standard instruments such as ADOS-G or AUTI-R.

It is not a question of refining or recalibrating, it is a question bout wether these diagnostic tools have an credibility at all as diagnostic tools.

I'll leave again with the question you cannot answer, name one of the twelve isolated symptoms for Autistic Disorder published in DM-IV that is specific to autism.

Michelle Dawson said...

In reponse to RAJ, there are replicated findings in autism epidemiology, among other areas.

So far as I can tell, according to RAJ, no diagnostic criteria or instrument based on observable behaviour can be useful unless it consists of only one observable trait. I disagree.

Also, see my first response to RAJ above, re phenocopies and so on.

KeithABA said...

Your classic dance Michelle (between you and Raj). You are not answering the question.

Instead you create a straw man. You summate Raj's argument (incorrectly) with your traditional "According to _____," statement. Then you attempt to disprove it.

What you fail to ever realize is that your summarization is "According to Michelle Dawson, Raj thinks there should be no consistent findings in the autism literature across time."

Raj is pointing to the innadequacy of the diagnostic criteria. (If I am understanding correctly Raj!) And how that may have played a role in the reported increase.

Michelle Dawson said...

In response to Keith ABA, here is RAJ's position in RAJ's own words:

"The narrow definition of ‘autism’ was not broadened, it was completly abandoned in 1994 with the removal of Kanner’s criteria."

Also, RAJ clearly takes the position that current diagnostic critieria are flawed to the point of being useless.

RAJ's positions come with predictions. One would be that there could not be replicated findings over time or (currently) across different research groups in autism.

I cited a series of papers from different groups and decades (spanning pre-DSM to DSM-IV-based autism diagnoses) to point out that this might not be a good prediction.

One way to test an idea is to look at the predictions it makes, and sometimes this is possible using existing data. Keith ABA seems to object to this kind of science-based thinking.

Also, RAJ claimed that "Ther is no REPLICATED findings with respect to epedemiology or prevelance rates since 1994." I pointed out that this claim is false. Anyone who is interested can test this by reading the relevant literature.

KeithABA said...

A much better formulated argument.

What do you mean when you say, "...no consistent findings in the autism literature across time. But this is not the case."

Are you referring to studies that point out similar deficits, or similar prevelance? I don't have access to the articles you referenced at this time.

Michelle Dawson said...

Keith ABA wrote, "A much better formulated argument."

I didn't change anything.

Keith ABA quoted me then wrote, "Are you referring to studies that point out similar deficits, or similar prevelance?"

In the quoted bit, I was referring to neither. The four papers I cited all report the same specific autistic cognitive strength.

I haven't yet provided examples of replicated findings in post-1994 autism epidemiology. Here are a few: Chakrabarti and Fombonne (2001, 2005), Baird et al. (2000), Bertrand et al. (2001), Ellefsen et al. (2007), Williams et al. (2008). You could throw in the two 2007 CDC studies.

RAJ said...

"I haven't yet provided examples of replicated findings in post-1994 autism epidemiology. Here are a few: Chakrabarti and Fombonne (2001, 2005"

Lets look at what Fombonne et al actually reported with respect to prevelance of ASD's in 2001 and 2005.

In the 2005 study they report that incidence is stable compared to the incidence reported in their 2001 study.

Both groups were diagnosed post the introduction of DSM-IV, the critical year when prevelance rates skyrocketed.

The 2005 stdy concluded:

"CONCLUSIONS: The rate of pervasive developmental disorders is higher than reported 15 years ago. The rate in this study is comparable to that in previous birth cohorts from the same area and surveyed with the same methods, suggesting a stable incidence".

Here is the conclusions from the 2001 study:

"CONCLUSIONS: Our results suggest that rates of PDD are higher than previously reported. Methodological limitations in existing epidemiological investigations preclude interpretation of recent high rates as indicative of increased incidence of these disorders although this hypothesis requires further rigorous testing".

Both studies included children diagnosed post 1994 the year diagnosic crieria removed Kanner's definition 'A pervasive lack of responsivenss to other people - autism' which was a requirement in DSM-III (1980) and replaced it with the vague, ambigous and subjective 'qualitative impairment in social reciprocity'

Both studies used the same diagnosic schemes so there should be a stable incidence when the same diagnostic schemes are used (DSM-IV).

Both studies also reported the incidence rates are higher than prevelance rates fifteen years ago (pre 1994).

Incidence rates, according to Fombonne himself, are not stable pre and post 1994 diagnostic schemes.

There is a large group of children who pre-1994 were variously described as 'brain-injured children' who remained without any specific diagnosis. This group represents the large increase in incidence rates pre and post 1994 diagnostic schemes and who are now given the fashionable label of Autism Spectrum Disorders.

You still havent answered the question.. Name one of the twelve isolated symptons listed in DSM-IV that is specific to 'Autism' that is not found in any other group of neurologically impaired people, including adult stroke patients, Romanian orphans who were subject to extreme emtional deprivation, Down's Syndrome children, mentally retarded Fragile X boys etc, none of whom met diagnostic criteria for 'autism prior to 1994.

Joseph said...

Raj is pointing to the innadequacy of the diagnostic criteria. (If I am understanding correctly Raj!) And how that may have played a role in the reported increase.

Yes, you misunderstand, Keith. RAJ believes there's something called "real autism" that is not the same as currently defined. From what he says, it's apparent "real autism" is autism as defined by Kanner or close to it.

Of course, there's no reason to believe Kanner's criteria had any less problems or was more advanced or more researched or more practical and useful than current criteria.

RAJ also seems to believe that certain characteristics should be required for someone to be called autistic, in a real sense, e.g. not being married. Yet, not even Kanner autism meets RAJ's requirements in that case.

RAJ said...

I'll leave this debate with a final observation:

A problem that cannot be defined cannot be solved.

Michelle Dawson said...

RAJ's contention, in RAJ's own words, is that:

"Ther is no REPLICATED findings with respect to epedemiology or prevelance rates since 1994."

This is incorrect; see the studies I cited above. The two Chakrabarti and Fombonne (2001, 2005) studies can be considered as one for this purpose. And neither of these studies is an incidence study.

I disagree with RAJ that for a diagnosis to be valid, it must consist of only one observable trait that cannot appear in any other individual. After all, people in comas show a pervasive lack of responsiveness to other people, as do people under general anesthetic. And Kanner had more than one criterion for autism ( Kanner & Eisenberg, 1956).

There is no way to make a clinical diagnosis of Rett syndrome (which continues to require clinical diagnosis) with only one of the current diagnostic critieria. Does this mean Rett's is a non-valid diagnosis?

Techskeptic said...

Name one of the twelve isolated symptons listed in DSM-IV that is specific to 'Autism' that is not found in any other group of neurologically impaired people

Can someone explain this to me? I have no idea what he is going on about...

Can you name one of the 5 symptoms of a cold (headache, stuffy sinus, sneezing, coughing, sore throat) that specific to a cold that is not found in any other respiratory sickness?

Rob Wilson said...

I would have thought that the right question here wasn't "Name one of the 12 criteria/symptoms ..." but whether that cluster of criteria/symptoms, or some sufficient subset of them, adequately (e.g., uniquely) picks out a phenomenon. That's because criteria/symptoms ALWAYS recur, individually, in different conditions and diseases, just like properties do in general for things classified in one way, rather than another. Anyway, that's one question: call it the synchronic question about autism as a category. We can then ask about whether the different things called "autism" at a time are instances of the same phenomenon. We can do this for breast cancers, for personality types, for relationship kinds (e.g., spouse).

But there's also another question here--the diachronic question--about the incidence of something called "autism" over time, and so as reported in studies at different times. If reported rates of prevalence change radically over time, then here are some options: (a) there's over-reporting at some times, but not others (b) under-reporting at some times, but not others (c) the actual prevalence rates increase / decrease over time (e.g, HIV / AIDS), or (d) the category is misconceived, in that it doesn't correspond closely enough to something in the world (e.g., witches).

So far as I can see, you have to answer the synchronic question positively--yes, there is this real cluster of properties that you find in people in different circumstances--before you can take up the diachronic question. But looking for individual, unique criteria / symptoms, just seems like a red herring.

Does any of this seem right to others here?

Michelle Dawson said...

For some reason, I wasn't alerted to an autism-politics-standard defamatory comment that was posted here I-don't-know-when. I've just deleted it. Many apologies.