Estimated autism prevalence in Northern Ireland: 3.3% for 2018-2019

The BBC news headline reading "Autistic children in NI schools trebles in a decade" provides the blogging fodder today.

NI refers to Northern Ireland, and the news report relates to the publication of further findings from the Department of Health in NI [1] on the topic of autism prevalence among school-aged children.

I've covered the NI 'autism in school children' figures for quite a few years on this blog (see here and see here). The stats have gone from 2.3% in 2015/2016 to 2.5% in 2016/2017 to 2.9% in 2017/2018 to the most recent figures of 3.3% in 2018/2019. The report and news coverage focus on how that recent 3.3% figure compared with 1.2% back in 2008/2009. That's quite a shift in the space of just a decade.

A few details are worthy of further mention. First, Northern Ireland seems to be taking a bit of a lead in collecting information about rates of autism in school-aged children (see here). Indeed, many of the 'home countries' making up the United Kingdom (UK) are starting to ask the questions that England, unfortunately, is seemingly not yet asking (see here).

Second, we are told that: "The increase in prevalence of children with autism can be attributed to an annual average increase in the number of children identified with autism of 12% between 2009/10 and 2018/19, against a background of a relatively static school population." This means that the rates of autism in school-aged children are not simply increasing because the school population as a whole is increasing. Indeed, with other not-so-long-ago chatter about long waiting lists for assessment in places like Northern Ireland (see here), one could argue that the current figures are an under-estimate.

Third, with regards to the sex ratio (boys:girls), the 2018/2019 figures suggest that "5.1% of males were identified with autism compared to 1.5% of females." The same figures a decade ago (2008/2009) were 1.9% and 0.4% respectively. I don't however necessarily agree with the: "Autism could therefore be considered to be an extreme of the normal male profile" sentiments expressed by the author to account for this difference but...

Fourth, the rate of the increase across the decade (2008/2009 compared with 2018/2019) was present in every school year. The author focuses in on the fact that nearly 4% of those in Year 6 (the end of primary school) were "identified with autism". He also mentions that most identification of autism in school is occurring when children are aged between 5 and 10 years old. Primary school, it seems, is an important time for the identification of autism.

Fifth: something approaching grading a child for autism 'severity' is also discussed. I know 'severity' is still a contentious issue (someone actually suggested 'severe autism' should be replaced by 'profound autism' which sounds rather sensible). Special educational need (SEN) assessment is a process via which a child's needs are graded. More details about this process applied to Northern Ireland can be found here. SEN stage 4 and SEN stage 5 indicate that a child requires support from school but also that "the education authority shares responsibility with the school." Nearly two-thirds of children identified with autism were at SEN stage 5. This was however down from previous years with the main 'growth' being among those who were gauged at SEN stage 2 and stage 3. The authors caution that such figures are only a snapshot (children can move up and down the SEN stages for example).

Whichever way you cut it, the recent figures out of Northern Ireland show the increasing trend for autism in school-aged children (see here). We can add such figures to those which have recently come out of the United States (see here and see here), Canada (see here) and various other parts of the world. We can quibble about the old 'better awareness' arguments and even diagnostic switching as being primary causes of the increase. I personally do not believe that such explanations even come close to the final reasons for the increase in cases that have been noted and continue to be seen (see here). What I do know is that further finance and resources are required to meet the often complex needs of these children and young adults to allow them to reach their potential.

And minus any emotive language (i.e. tsunami), let's remember that children turn to adults, and many of these children will require on-going help and support into their later years. The question is: are we prepared?

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[1] Waugh I. The Prevalence of Autism (including Asperger Syndrome) in School Age Children in Northern Ireland 2019. Northern Ireland Department of Health. 2019. May 10.

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Autism, learning disability and diagnostic substitution

The findings reported by Cynthia Nevison and Mark Blaxhill [1] represent the source blogging material today. Their quite detailed analysis of individual state data based on the "United States Individuals with Disabilities Education Act" (IDEA) is front and centre and what it might mean for the argument that the quite phenomenal rise in diagnoses of autism or autism spectrum disorder (ASD) is due wholly or in part, to a switch from the diagnosis of intellectual (learning) disability to autism.

Based on examining IDEA data for each of the 50 states of the United States covering various years, various years of birth and various ages, authors concluded that sweeping generalisations about widespread diagnostic switching/substitution were not necessarily borne out in such State level data analysis. They did find that: "Nationwide ID [intellectual disability] prevalence declined steeply over the last two decades, but the decline was driven mainly by ~15 states accounting for only one-fourth of the U.S. school population." Further, when assigning specific statistical conditions to states based on things like the decrease in ID being comparable to the increase in autism diagnoses or the increase in autism diagnoses being substantially greater than the decrease in ID diagnoses, authors reported a complex picture generally pertinent to the idea that "ID prevalence stayed relatively constant while ASD prevalence rose sharply."

This is not the first time that some of these authors have used IDEA data to put forward a view that the increase in cases of autism is real and not just an artifact of changing diagnostic criteria for example (see here). Indeed, both authors have an interest in this area [2] and dedicated some peer-reviewed science time to it. Personally, I find this kind of detailed scrutiny to be refreshing in these days of sweeping generalisations and soundbites about many facets of autism. Indeed, as time goes on and the numbers of those being diagnosed with autism creep ever higher worldwide (see here), older arguments about diagnostic substitution have seemingly become less and less convincing. No, diagnosticians weren't that bad at diagnosing autism X number of years ago...

Having said that, I do still think there is a place for diagnostic substitution when it comes to explaining *some* of the increase in cases being diagnosed. Data such as that from King & Bearman [3] estimating that about a quarter of the increase in cases of autism in places such as California might be due to diagnostic switching from ID cannot simply be forgotten or brushed under the scientific carpet. I should also mention that autism can very well exist in the presence of ID too (see here); even more so in specific populations (see here).

I know that old battle lines about a real vs. artificial increase in cases of autism still persist in many circles and I understand some of the reasons why each side believe what they believe. What is however not in dispute, is the fact that there are quite massive numbers of people (children and adults) being diagnosed as on the autism spectrum year-on-year worldwide (with additional many unable to access timely and appropriate diagnostic services) and resources aplenty are required to identify their specific needs and provide accordingly. No easy task in these continuing days of austerity, cuts and the like...

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[1] Nevison CD. & Blaxill M. Diagnostic Substitution for Intellectual Disability: A Flawed Explanation for the Rise in Autism. J Autism Dev Disord. 2017 Jun 6.

[2] Blaxill MF. What's going on? The question of time trends in autism. Public Health Rep. 2004 Nov-Dec;119(6):536-51.

[3] King M. & Bearman P. Diagnostic change and the increased prevalence of autism. Int J Epidemiol. 2009 Oct;38(5):1224-34.

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Autism diagnoses (and diagnostic stability) in Germany

"From 2006 to 2012, the prevalence of autism spectrum disorder diagnoses in 0- to 24-year-olds increased from 0.22% to 0.38%."

That was one of the details included in the rather interesting paper by Christian Bachmann and colleagues [1] who provided some introductory information on the the trends in autism diagnoses in Germany. I say 'introductory information' because it appears that autism or autism spectrum disorder (ASD) has not exactly received the research attention in Germany that it perhaps has in other similarly developed nations such as the United States or here in Blighty. Indeed, as Bachmann et al note: "Due to the only available study to date, the prevalence of ASD in Germany is estimated to be about 0.25% in 0- to 24-year-olds in 2009" and even that was taken from another study by the author [2].

This time around, the authors listed two primary aims for their research: (a) "to establish the time trends in the administrative prevalence of autism spectrum disorder diagnoses" and (b) "to assess the stability of autism spectrum disorder diagnoses over time." I'm interested in both these areas on this blog (see here for example). Data for the time trends part of this research came from "the German statutory health insurance company Allgemeine Ortskrankenkassen (AOK) from the years 2006 to 2012" where a diagnosis of ASD was registered by ICD-10 definition. Data for the stability side of their research was via a "cohort with a first-time diagnosis of autism spectrum disorder in 2007 through 2012, investigating the percentage of retained autism spectrum disorder diagnoses."

Results: well as per the opening sentence to this post, the only way is up when it comes to the estimated prevalence of autism or ASD despite the figures being a tad lower than those for other countries. Those percentages were based on nearly 15,000 ASD diagnoses being recorded in 2006 out of 6.9 million insurees, and nearly 22,000 ASD diagnoses in 2012 out of 6.4 million insurees. Males were quite a bit more likely to be diagnosed with autism/ASD and prevalence peaked for the age group 6-11 year olds.

Then to that stability part of the study and from "3927 patients (mean age: 8.7 years, 68.9% males)" with a specific ASD diagnosis in 2007 only a third 'carried on' with a specific diagnosis by 2012. The authors note: "This figure is lower than the usual persistence for ASD diagnoses, which is about 73%–100%." Lower? Yes, I'd say. The reasons for this quite notable lack of diagnostic stability? Well, the authors note that there is probably going to be more than one (before anyone makes any sweeping generalisations). They talk about the lack of "specialised mental health services that are competent to diagnose ASD according to international standards and guidelines" as one factor. They talk about diagnoses "often made by paediatricians or occupational therapists, without employing diagnostic gold standards like Autism Diagnostic Observation Schedule (ADOS)." They even talk about diagnostic switching between ASD subgroups as potentially also being a factor to consider. And then another possibility: "Other reasons include improvement of symptoms because of successful therapeutic interventions" without any specific mention of what types of therapeutic intervention might be involved. Sounds very 'optimal outcome' to me (see here). In short, it's probably going to be complicated.

Bearing in mind those diagnostic stability figures and the authors reliance on a database that relied on those unstable figures for prevalence estimates, this is interesting research. It shows that even a social and economic powerhouse like Germany still has some way to go in many areas not least with that related to autism. Where next? Well, as per the authors suggestion: "one possible option could be to establish standardised diagnostic algorithms and certify ASD diagnostic centres who employ these standards." Sounds good but in amongst the chatter about autism 'misdiagnosis' and seemingly 'ill-trained' professionals diagnosing, I do wonder whether further, more detailed, investigations are needed on the autism diagnostic stability figures of Germany and whether it's all just due to administrative errors...

Music to close, and this guy was/is apparently quite big in Germany...  Permit denied!

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[1] Bachmann CJ. et al. Diagnoses of autism spectrum disorders in Germany: Time trends in administrative prevalence and diagnostic stability. Autism. 2016. Dec 20.

[2] Bachmann CJ. et al. Psychopharmacological treatment in children and adolescents with autism spectrum disorders in Germany. Res Dev Disabil. 2013 Sep;34(9):2551-63.

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Christian J Bachmann, Bettina Gerste, & Falk Hoffmann (2016). Diagnoses of autism spectrum disorders in Germany: Time trends in administrative prevalence and diagnostic stability Autism: International Journal of Research & Practice : 10.1177/1362361316673977

Prevalence of learning disability and autism in Western Australia

"The prevalence of ID [intellectual disability] in WA [Western Australia] has increased over the past 10 years compared with previous estimates... This increase is associated in a large part with an increased prevalence of ASDs [autism spectrum disorder] for whom 70% had comorbid ID or an unknown level of ID."

Those were some of the findings reported by Jenny Bourke and colleagues [1] (open-access available here). Drawing on data derived from the Intellectual Disability Exploring Answers (IDEA) database, a resource designed to 'provide high-quality complete and population-based information on Western Australians with an intellectual disability', authors set about looking at cases of ID for those born between 1983 and 2010. Intellectual disability (ID) - sometimes called learning disability here in Blighty - is typically diagnosed when IQ is assessed as being below 70 where a score of between 55-69 denotes mild ID, a score of between 40-54 denotes moderate ID and a score below 40 denotes severe ID. Authors were also able to cross-reference cases with information in other databases in terms of race, gender and location of birth.

Results: covering a total of nearly 750,000 live births during the period of inspection, some 10,000 infants "were identified with an ID by 2010." This equated to a total prevalence of ID of 17 per 1,000 live births. Most cases of ID were defined as being mild or moderate in terms of IQ scores (where available) and when compared to previous data from this authorship group [2] authors reported "an overall increase in prevalence of ID of 19% from 1999 to 2010."

Insofar as the possible causes of ID, various factors are reported to be potentially contributory including ID accompanying Down's syndrome, ID linked to various other genetic/chromosomal issues, birth defects and infection(s). Increasing preterm birth and survival rates are also suggested to be another contributory factor. The authors also add: "It is also possible that a proportion of the observed increase in mild or moderate ID may be attributable to un-diagnosed Fetal Alcohol Syndrome."

The link between autism and ID is also discussed by Bourke et al. On the basis of other research (see here) suggesting that approximately 30-40% of cases of autism will also include a degree of ID, I was pretty interested to see the authors of this latest research suggesting something a little bit different. To quote: "Of the 2307 [diagnosed with an ASD], 675 (29.3%) definitely did not have an ID." I've underlined the word 'not' because the implication is that up to 70% of those with autism did have some level of ID. I say this bearing in mind that Bourke did include children diagnosed with an ASD where "children with an autism diagnosis but an unknown level of ID were classified within the comorbid ASD and ID group." But how far will the true figure of autism and ID combined fall by excluding such unknowns?

There is just one more detail of the results that I want to draw your attention to with regards to ID: "The prevalence for Aboriginal children was 39.0/1000 compared with 15.7/1000 for non-Aboriginal children." The idea of disparities in rates of ID among Indigenous Australians and other groups is not necessarily a new one as per other research [3] and strengthen calls for a lot more research focus on this and other groups [4] from a variety of different clinical perspectives.

In terms of what to make of these combined findings, I'd like to think there are some important issues requiring further study. The idea that autism and ID can and do frequently co-exist is paramount to discussions. We can talk and discuss about the hows and whys until the cows come home but the link remains strong and indeed, among different populations, might be more variable [5] than previously suggested. Also, for many years in autism research circles, there have been discussions upon discussions about how the quite spectacular rise in autism cases (including that in Australia) might have been at the expense of diagnostic switching from categories such as ID. The Bourke data seem to suggest that not everywhere in the world is necessarily experiencing a corresponding 'drop' in cases of ID supportive of this diagnostic switching argument. Indeed, I'm minded to suggest that one has to be quite careful about explaining away any 'real increase' in autism cases solely using the ID switching argument (see here)...

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[1] Bourke J. et al. Population-Based Prevalence of Intellectual Disability and Autism Spectrum Disorders in Western Australia: A Comparison With Previous Estimates. Medicine (Baltimore). 2016 May;95(21):e3737.

[2] Leonard H. et al. Prevalence of intellectual disability in Western Australia. Paediatr Perinat Epidemiol. 2003 Jan;17(1):58-67.

[3] Leonard H. et al. Autism and intellectual disability are differentially related to sociodemographic background at birth. PLoS One. 2011 Mar 30;6(3):e17875.

[4] Bennett M. & Hodgson V. The missing voices of Indigenous Australians with autism in research. Autism. 2016 May 25. pii: 1362361316643696.

[5] Postorino V. et al. Intellectual disability in Autism Spectrum Disorder: Investigation of prevalence in an Italian sample of children and adolescents. Research in Developmental Disabilities. 2016; 48: 193-201.

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Bourke J, de Klerk N, Smith T, & Leonard H (2016). Population-Based Prevalence of Intellectual Disability and Autism Spectrum Disorders in Western Australia: A Comparison With Previous Estimates. Medicine, 95 (21) PMID: 27227936

Social communication disorder (SCD) reviewed

Sometimes I believe in as many as
six impossible things before breakfast.

A micropost if you will, for today, and a link to a potentially very important paper by Lauren Swineford and colleagues [1] (open-access) talking about the diagnostic concept: social (pragmatic) communication disorder (SCD) and it's various crossings with language impairments and autism spectrum disorder (ASD).

SCD, as I've indicated in other posts (see here and see here) is something that the autism community in particular, is going to be hearing a lot more about in the coming years, derived from the latest DSM-5 schedule.

Just one choice quote to offer from the Swineford paper: "Evidence of SCD was provided in the DSM-5 field trials, which indicated that a decrease in DSM-IV ASD diagnoses was accounted for by movement to SCD diagnostic category." Yes, it appears that this is already happening...

Some music then... Johnny Marr - Getting Away With It.

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[1] Swineford LB. et al. Social (pragmatic) communication disorder: a research review of this new DSM-5 diagnostic category. Journal of Neurodevelopmental Disorders 2014, 6:41.

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Swineford, L., Thurm, A., Baird, G., Wetherby, A., & Swedo, S. (2014). Social (pragmatic) communication disorder: a research review of this new DSM-5 diagnostic category Journal of Neurodevelopmental Disorders, 6 (1) DOI: 10.1186/1866-1955-6-41

Autism in the UK: levelling off?

A short post today based on the paper by Brent Taylor and colleagues* (open-access) adding to the considerable literature on the autism numbers game. The headlines generated from this study are no better encapsulated than that of the BBC: "UK autism cases have 'levelled off'".

Reaching the summit? @ Wikipedia

The crux of the paper is that based on an analysis of the UK General Practice Research Database (GPRD) which carries details of several million patient records following patient contact with what's known as a General Physician (GP) here in the UK, cases of autism spectrum disorder included in those records were counted and annual prevalence and incidence rates based on 8-year olds were generated.

The results: cases of autism recorded on the GPRD suggested that "the annual prevalence of autistic spectrum disorders was estimated at 3.8 per 1,000 boys and 0.8 per 1,000 for girls".

Importantly, from the BBC: "The study concluded there was "compelling evidence that a major rise in incidence rates of autism, recorded in general practice, occurred in the decade of the 1990s but reached a plateau shortly after 2000 and has remained steady through 2010"".

There are also a few interesting nuggets of information to take from the Taylor paper such as the reason(s) put forward for the dramatic increase in cases witnessed during the 1990s. Another quote I'm afraid on whether greater awareness or broadening diagnostic criteria or diagnostic substitution were the sole causes of the increase: "it seems unlikely that these factors materially explain the extraordinary increase in the number of children diagnosed in the 1990s; nor the steady state that followed thereafter in 2004 through 2010". This is in line with what other commentators have talked about (see here).

The Taylor paper is an interesting one and no doubt will generate some discussion about the numbers of cases of autism. I note that the figures reported by Taylor and colleagues are somewhat at odds with other studies using different data collection methods based in other parts of the world such as that 1 in 50 figure in the US discussed quite recently (see here) or other incidence data (see here). Whether this is down to how the data are collected and verified or truly representative of differing rates of autism in different geographical populations is yet more substance for discussion.

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* Taylor B. et al. Prevalence and incidence rates of autism in the UK: time trend from 2004–2010 in children aged 8-years. BMJ Open. 2013; 3: e003219

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Brent Taylor, Hershel Jick, Dean MacLaughlin (2013). Prevalence and incidence rates of autism in the UK: time trend from 2004–2010 in children aged 8-years BMJ Open DOI: 10.1136/bmjopen-2013-003219

Canada and the autism prevalence rate continued

So, in my last post this morning I was talking about the paper by Hélène Ouelette-Kuntz and colleagues* on the autism numbers game in various regions of Canada. Thanks to Natasa, I now have the full-text of the paper and just wanted to pass some further comments on the findings reported and potentially how important they might be.

• OK, three regions in Canada were scrutinised based on the NEDSAC initiative for cases of autism: Newfoundland and Labrador (2003-2008 period), Prince Edward Island (2003-2010) and Southeastern Ontario (2003-2010) and a total of 2377 cases of autism were identified across various age groups (2-5 years, 6-9 years, 10-14 years). Response rates - to get more detailed information about the children identified with an autism spectrum disorder (ASD) - per region were not exactly great but ranged between 32% and 45%.
• The prevalence of autism "increased significantly among all age groups" over the various surveillance periods. There were however some variations across the different regions such that for example, prevalence in the age group 2-5 years old in Southeastern Ontario did show something like a plateau in the later years of study. The authors however do not rule out "incomplete capture of preschool children with autism" as accounting for their results there. Indeed Southeastern Ontario was reported to also have contributed a "larger proportion of false positive" diagnoses based on some small-scale case validation investigation using ADOS or ADI as the standards which may also have accounted for some of the final figure they report.
• Age of diagnosis and the issue of diagnostic delay are covered in the data presented. Another quote: "in all three regions many children were not diagnosed until they were older". So much for the practical application of all those 'catch 'em early' sentiments.
• The authors pass comment on the issue of age at diagnosis as affecting any prevalence estimates using the Parner paper** as an example and the suggestion that a younger age at diagnosis would artificially inflate the prevalence rate for that age group. Allowing for potential bias in the reporting of age at diagnosis they concluded: "it does not appear that an earlier age at diagnosis contributed in any meaningful way to prevalence increases in the youngest age group".
• The sex ratio also came under scrutiny. Interestingly that Icelandic study*** also looking at autism prevalence rates which I mentioned in my last post seemed to take an interest in one of my studies on the topic (see here****). The Icelanders decided that their results did not accord with our own where we talked about an widening gap in the gender ratio towards boys over the years. The Canadian study reported that "the boy:girl prevalence ratio increased between the first and final years of the surveillance period". Indeed in one region Prince Edward Island the ratio went from 3.7:1 in 2003 to 6.7:1 in 2010 (peaking at 6.9:1 in 2009). I'm don't want to say too much about this for now bearing in mind all the possible confounders which could account for results, but certainly if I were an official based somewhere in Prince Edward Island I'd be minded to ask a few questions about the hows and whys of these findings. 
• The authors admit that the various explanations they've looked at as accounting for the increase in cases "appeared to account for only a small portion of the increases observed". In other words, the numbers are going up but to say that it is better awareness or just that kids are being diagnosed earlier or that it is diagnostic reclassification (which doesn't really cover the period of this study in terms of DSM or ICD changes for example) doesn't really cut the mustard when looking at the size of the increase they uncovered. I'll leave you to determine what else might be able to account for the increase they reported.

I'll finish by reiterating that the autism numbers game is a complicated area. One has to be careful not to make too many sweeping generalisations on how figures, and the potential reasons for those figures, in one area are necessarily representative of autism prevalence in all other areas. 

That being said, the Ouelette-Kuntz paper does perhaps indicate that we should perhaps be widened the debate about why autism is on the rise above and beyond the notion that we're just better at finding it. Yes, there are factors like socio-economic status (SES) to consider but dare I even mention that we might also start to take seriously how environment (however you wish to define this) might also be impacting on the numbers of cases being diagnosed and indeed the concept of gene - environment interactions***** (open-access)?

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* Ouellette-Kuntz H. et al. The changing prevalence of autism in three regions of Canada. J Autism Dev Disord. 2013 Jun 16.

** Parner ET. et al. A comparison of autism prevalence trends in Denmark and Western Australia. J Autism Dev Disord. 2011 Dec;41(12):1601-8. doi: 10.1007/s10803-011-1186-0.

*** Saemundsen E. et al. Prevalence of autism spectrum disorders in an Icelandic birth cohort. BMJ Open. 2013 Jun 20;3(6). pii: e002748. doi: 10.1136/bmjopen-2013-002748.

**** Whiteley P. et al. Gender Ratios in Autism, Asperger Syndrome and Autism Spectrum Disorder. Autism Insights. 2010:2 17-24.

***** Chaste P. & Leboyer M. Autism risk factors: genes, environment, and gene-environment interactions. Dialogues Clin Neurosci. 2012 September; 14(3): 281–292.

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Ouellette-Kuntz H, Coo H, Lam M, Breitenbach MM, Hennessey PE, Jackman PD, Lewis ME, Dewey D, Bernier FP, & Chung AM (2013). The changing prevalence of autism in three regions of Canada. Journal of autism and developmental disorders PMID: 23771514

Canada and the autism prevalence rate

[Update: 01/07/13: Further discussion on this topic can be found here].

The autism numbers game has been a long running discussion in many quarters. Even with estimates now suggesting that anywhere between 1 in 88 children or 1 in 50 children (or 1 in 57 if you prefer) in the United States (depending on who and how you count) might present with an autism spectrum condition, arguments still rage about the hows and whys, often over and above the question: 'what are we going to do about it'.

Waterloo Bridge @ Wikipedia 

I'm sitting on the fence a bit about why the numbers are increasing as they are. I appreciate that we are better at detecting autism than we were 30 or 40 years ago and all the related opinions about changes in diagnostic schedules (see here) and reclassification from other conditions in favour of the autism spectrum. There is little doubt that these factors exert an effect and are probably going to be significant ones.

Having said that though I'm not yet ready to give up on the idea that some of the increase in cases is due to other factors including being representative of a true and real increase in cases. My reasoning for this opinion is multi-faceted but includes the fact that we have, at least in the Western world, more than adequate provisions for the detection of [pediatric] autism and to say that its all about reclassification or awareness really brands our autism diagnosticians as being pretty incompetent over the years. They're not by the way; indeed they do a sterling job often in very, very difficult circumstances. What I should also point out is that the reasons for the increase might not necessarily be the same for every part of the world.

Just before also you tell me there is no evidence that the incidence - not prevalence - of autism is increasing, I beg to differ as per some of my previous posts which can be seen here and here. Indeed this leads into an interesting paper that has recently appeared by Hélène Ouelette-Kuntz and colleagues* on the prevalence rate of autism in several regions in Canada which forms the topic of this post.

I'll admit to not having the full-text of the Oueltte-Kuntz paper so you might need to do some further fact-checking on any conclusions that I reach. Actually, the chances are that I'm probably not going to reach any conclusions on the paper so maybe this is a moot point.

The first thing that we do get from the abstract to the paper is that based on an analysis of data from the National Epidemiologic Database for the Study of Autism (NEDSAC) (yes same author) autism prevalence is increasing in this study. That increase in annual prevalence ranges from 9.7% up to 14.6% I assume because of the differing prevalence rates among the different regions of Canada the study authors looked at.

The next thing to glean from the abstract are some of the reasons put forward to account for the increase: previously unidentified cases being identified and the issue of "in-migration" which concerns movement between regions of the same country/territory.

Finally, a quote: "we cannot rule out the possibility of a true increase in incidence, particularly given the lack of a leveling-off of prevalence among the 6- to 9-year olds". In other words, the door is still open to a 'real' increase in cases being contributory to the numbers.

I'm sure the arguments will continue about the hows and whys of the autism numbers game. One thing is abundantly clear from most of the emerging data: autism is fast becoming a 'common condition' as per another recent report on the autism numbers game from Evald Saemundsenand and colleagues** (open-access) and a particularly interesting table. As we stand at the moment, we don't really know all the reasons why and what to do about it.

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* Ouellette-Kuntz H. et al. The changing prevalence of autism in three regions of Canada. J Autism Dev Disord. 2013 Jun 16.

** Saemundsen E. et al. Prevalence of autism spectrum disorders in an Icelandic birth cohort. BMJ Open. 2013 Jun 20;3(6). pii: e002748. doi: 10.1136/bmjopen-2013-002748.

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Ouellette-Kuntz H, Coo H, Lam M, Breitenbach MM, Hennessey PE, Jackman PD, Lewis ME, Dewey D, Bernier FP, & Chung AM (2013). The changing prevalence of autism in three regions of Canada. Journal of autism and developmental disorders PMID: 23771514

1 in 50 children with parent-reported autism in the US

An estimated 1 in 50 US children aged between 6 - 17 years old present with an autism spectrum disorder (ASD). Attention-grabbing isn't it?

Today's post is based on the source of that soundbite, the publication by Stephen Blumberg and colleagues* (open-access) describing results from data mining of the 2007 and 2011-2012 US National Survey of Children's Health (NSCH) relevant to the numbers of cases of ASD.

Testing 1, 2, 3 @ Wikipedia  

The autism-numbers game is something that has been discussed previously on this blog; most recently with the CDC 1 in 88 estimate in mind (see here) and the even more recent data from New Jersey (see here). The direction of the figures seems only one way - up - but the reason(s) for the increase still remain the source of discussion.

The Blumberg report is open-access, but a few pointers might be useful:

• Based on 91,642 telephone interviews in 2007 and 95,677 interviews between 2011-2012, parental reports of receipt of an ASD diagnosis (autism, Asperger syndrome, PDD) in offspring were noted, alongside other variables such as age of the child, severity of presentation (mild, moderate, severe) and aged when first diagnosed.
• Actually in the age range 6-17 years old, data were collected from 63,967 interviews (2007) and 65,556 (2011-2012).
• Results: "based on parental reports, the prevalence of diagnosed ASD in 2011-2012 was estimated to be 2.00% for children aged 6-17". This compared with 1.16% or 1 in 86 for 6-17 year olds in 2007.
• The increase in prevalence was noted across the age ranges when they were sub-categorised and perhaps not surprisingly, there was a greater increase in prevalence in boys (2007: 1.8% vs. 2011-2012: 3.23%) than girls (2007: 0.49% vs. 2011-2012: 0.70%). Reported severity also shifted between the various data points (and age ranges) indicating that there was a trend towards less severe presentation (milder ASD) post 2008 diagnosis.
• The authors were able to some degree, rule out "survey-based measurement error" as being a major contributor to the prevalence increase and there is some discussion about the data not necessarily reflecting "factors that exist prior to or occur just after birth". Indeed the authors very firmly suggest that the changes are a consequence of either "recognition of ASD by health professionals or survey-based measurement changes over time". They also conclude that increases in the prevalence of parent-reported ASD especially for children aged 6-13 "was the result of diagnoses of children with previously unrecognized ASD".
• As per the report on this story in USA Today "15% to 20% of children who were once diagnosed with autism no longer have the condition". Which raises similar questions as to that of the Fein study on 'outgrowing autism' and 'optimal outcomes' which created so many column inches recently (see here and here).

Bearing in mind that this was a prevalence study not an incidence study (see here for the difference) and issues with regards to response rates (2007: 46.7% vs. 2011-2012: 23.0%), and the sole reliance on parental judgement of variables like severity, the data being presented are indeed stark.

That the rates of autism have seen an inordinate shift from what was once considered a rare condition to something which theoretically should [almost] appear in every school classroom at least once is an eye-opener. As mentioned, the debates rumble on about factors such as better awareness of autism, better case ascertainment, diagnostic switching and broadening, etc. as being the source of the increase. A real increase in cases? Hardly a mention in this latest data. The implication that for example our screening methods and skilled professionals have been able to miss or mis-diagnoses a staggering number of children presenting with an ASD is truly mind-boggling and worthy of an inquiry or two in the US and beyond. Indeed better be quick with that investigation with the DSM-V revision deadline fast approaching and the potential impact that might have on the autism numbers game (including adult numbers**).

So 1 in 50 children with an ASD. What happens next? Sure, many children were described as falling into the mild and moderate ability ranges but as I've said before, terms like 'high-functioning' don't necessarily mean 'can function' with regards to daily living skills, quality of life and onwards translating into positive outcomes in adulthood. Certainly society has to play its role in helping people with autism reach their potential (I have a post scheduled on job interviews and autism coming up soon) and changes are indeed on-going (e.g. the implementation of the Autism Act here in the UK). But let's not be too proud of the achievements done in this area, as still many people on the autism spectrum, their families and concerned others have to fight daily for appropriate recognition, provisions and services.

Another important issue also springs to my mind on the basis of the new prevalence figure. Comorbidity, of which autism is by no means immune from, are not mentioned. The realisation that autism is often very much more than the sum of its triad - soon to be dyad - in terms of comorbidity must surely factor into the potential impact of the latest figures. Not least because of the quite startling health inequalities which seem to be present when an ASD is diagnosed and how as was very recently detailed in the CIPOLD report, such inequality can in some cases, have the most profound and far-reaching effects. I'm not trying to scare anyone; just sayin' that we need to be mindful of the whole person not just their autism.

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* Blumberg SJ. et al. Changes in prevalence of parent-reported autism spectrum disorder in school-aged U.S. children: 2007 to 2011–2012. National Health Statistics Reports. 2013: 65.

** Wilson CE. et al. Comparison of ICD-10R, DSM-IV-TR and DSM-5 in an adult autism spectrum disorder diagnostic clinic. J Autism Dev Disord. March 2013.

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Wilson, C., Gillan, N., Spain, D., Robertson, D., Roberts, G., Murphy, C., Maltezos, S., Zinkstok, J., Johnston, K., Dardani, C., Ohlsen, C., Deeley, P., Craig, M., Mendez, M., Happé, F., & Murphy, D. (2013). Comparison of ICD-10R, DSM-IV-TR and DSM-5 in an Adult Autism Spectrum Disorder Diagnostic Clinic Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-013-1799-6

Autism prevalence increasing in New Jersey

A quote to begin with from the paper by Walter Zahorodny and colleagues* with special thanks to Natasa for the full-text of the paper on the prevalence of autism spectrum disorders (ASDs) in New Jersey: "Regardless of whether one acknowledges an increased ASD prevalence, all the epidemiological and administrative studies confirm that ASD is now among the most common, severe, developmental disorders".

Edison in his NJ workshop @ Wikipedia  

For me this quote encapsulates everything about the various autism prevalence (and incidence) debates which have been, and continue to be, rife particularly in cyberspace.

It kinda says, yep we don't know all the details behind the quite enormous rise in cases of autism - which lets face it, basically boils down to whether or not you believe environment in whatever form contributes to autism aetiology - but whatever the reason(s), autism is not an uncommon condition and has a huge range of implications stretching from the diagnosed individual, their families, their schools, their doctors through to society as a whole.

Indeed, the paper from Zahorodny has lots of other soundbites worthy of quoting, but just before I head out that way, a few snippets of information about the paper are in order:

• This was a study all about comparing the estimated prevalence of ASD in the New Jersey Metropolitan Area (NJMA) in 2002 with some newer data from 2006.
• The focus was on using "identical methods and procedures" between the two time points drawing on the ADDM method which included active-screening and subsequent independent case determination. 
• Children born in 1998 and residing in the study area in 2006, classified as being educated under any special education classification (equivalent to receiving a SEN) were the starting point, filtered down to those with a documented or suspected ASD diagnosis, whose data were subsequently subjected to clinician review and analysis. "Agreement between previous ASD diagnosis and ASD case status by the surveillance method was 99%".
• Results: In 2006, out of a population of 30,570 8-year olds, 3,332 child records were reviewed, 923 of which met criteria for further review, which identified 533 with study-determined ASD, equal to a prevalence of 17.4 per 1000 (1.7%). This compared with 2002 data (8-year olds born in 1994) suggestive of a prevalence rate of ASD of 10.6 per 1000 (1.1%). The data is a little confusing because two different estimates are given based on the use of curtailed and non-curtailed populations; one used a sort of comparator to assess any changes in population affecting the estimates. 
• Allowing for the slight differences, the authors determined that 1 in 57 8-year olds in NJMA in 2006 had an ASD and a "startling" 1 in 35 boys.
• Between the sexes, ASD prevalence in boys grew from 17 to 28.7 per 1000 between 2002 and 2006 and 4.1 to 5.9 per 1000 in girls. 
• Regression, that most interesting of phenomenon with autism in mind, was relatively unchanged; the rate hovering around the 20% of cases mark.
• Quite a few factors potentially influencing the numbers were also taken into account including migration. That on top of the fact that DSM-IV TR was the main assessment criteria across the time periods.

This is an interesting study for lots of reasons. Not least because using identical protocols and identical criteria, a change in the prevalence of ASD was noted over 4 years. One therefore, to quite a strong degree, also rules out changes in DSM diagnostic revisions as a cause of the changes and to some extent those arguments about widening criteria as was evidenced between DSM-III and DSM-IV. That being said, the issue of increased awareness and its impact cannot be ascertained from this data; indeed also diagnostic substitution to some extent also remains a possibility (i.e. from learning disability to autism) as does under-diagnosis of ASD in non-white groups. This last point however needs to be tempered by the authors demonstrating a 90% increase in cases of ASD among Black, non-Hispanic children but also indicating "a broadly based escalation of ASD, rather than an increase reflecting improved case-finding in specific populations".

I get the impression that the authors were hinting that the change they reported might be more administrative over real. So they say: "It is too soon to know at what point ASD prevalence will plateau", which implies to me that they are looking to the autism rate increase to somehow eventually 'bottom out' when the message finally gets through about autism awareness and what it is. I hope I don't seem too rude when I say that we've all been waiting for that plateau for quite a few years now so as to save those 'it must be better case ascertainment' arguments, but so far there is no end it sight at least according to the latest CDC estimates. I'm sure even the staunchest supporters of the better awareness et al camp would quite logically admit that at least part of the increase might not necessarily reflect just 'better awareness' and 'more diagnostic substitution' but rather some other factor or factors also being involved? Or maybe not....

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* Zahorodny W. et al. Increasing autism prevalence in metropolitan New Jersey. Autism. November 2012.

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Zahorodny, W., Shenouda, J., Howell, S., Scotto Rosato, N., Peng, B., & Mehta, U. (2012). Increasing autism prevalence in metropolitan New Jersey Autism DOI: 10.1177/1362361312463977

Assessing changes in autism (Bowie style)

'Ch-ch-ch changes' is perhaps one of the best Bowie songs (that and 'Starman'). The lyrics 'Time may change me, but I can't trace time' carrying many meanings, but for this post quite conveniently could be translated to describe how we all change over time but measuring the nature of that change is problematic.

More than once it has been stated that autism is a condition which is defined exclusively by the overt presentation of a specific set of behaviours anchored to a specific period of onset. The description of those behaviours might be due for a bit of an overhaul in the coming years with the various proposals attached to schedules like DSM-V, but essentially the same diagnostic features remain. When trying to assess core behaviours, there are a variety of schedules 'on the market'. Some of the gold standards like ADI-R and ADOS have appeared fairly frequently on this blog. I say 'gold standard' because when it comes to providing some standardised, objective (almost) data based on the defining behavioural and developmental features, these two instruments in particular have stepped up to the mark. Notable also because the level of autistic behaviours according to domain can be scored on each instrument and compared against cut-off values. There are other instruments that fit into the 'gold standard' category but I will stick with these two for now.

Fine for assessing behaviour in autism, but what about assessing change in behaviour in autism?

'Change' in symptoms in autism occurs quite readily for a variety of reasons. Aside from the early diagnostic instability which I have discussed in a previous post, change can occur as a result of maturation (remember my puberty post), as result of social and environmental factors and has also been suggested as a result of intervention (in some cases). I would imagine therefore that most people would not view autism as a static entity but something rather more dynamic.

The problems however start when change is evaluated; bearing in mind that change in autism normally is not just confined to the 'core' diagnostic symptoms but often, other peripheral presentations (indeed, one might argue that it is the knock-on effect from peripheral changes to core symptoms which is important). What do we do then?

The appropriateness of outcome measure has been discussed in the scientific literature. This paper discussed various issues including 'outcome measures sensitive to individual change'. The number of times I have come across papers that have found no significant effects for one thing or another but have then commented that the outcome measure may have missed target behaviours is beyond a joke. The problem is that when it comes to assessing change there is no universal 'gold standard' instrument. OK some researchers (including ourselves) have used instruments like ADOS. On the whole these are OK as long as you give a long enough period of time between assessment sessions so as not to encounter any practice effects. Bearing in mind also that ADOS was never really designed with measuring change in mind, so we are perhaps trying to fit a square block into a round hole.

The instruments that have been configured with change in mind, whilst also OK, also have their short-comings. The ATEC (Autism Treatment Evaluation Checklist) has been around for quite a while and used in quite a few studies, mostly concerned with the more 'biomedical' interventions. I have to say that I was always a little hesitant with the ATEC, thinking that perhaps it was not as standardised as it should be. Like a snob looking down at a fish and chip supper. My opinion has however changed in recent years and especially following the thumbs up from this study a few weeks back. Don't get me wrong, there are still quite a few shortcomings, particularly associated with the use of a 3-point Likert scale/item to assess behaviour and also in the definition of some of the items (how do you define 'constipation' and what if constipation to you is not the same as constipation to me?)

Another instrument, which I will readily admit has been a favourite of mine, is the Behaviour Summarized Evaluation (BSE) schedule. For some reason nearly all the links on the web mis-spell this instrument as the behavioural summarized, etc. I know, I know BSE... for us here in the UK conjours up cows in a pretty dire state and lots of quite distressing bonfires - not one of our finest hours. But the BSE instrument for autism is a pretty good scale and has the evidence to back it up (here and here). I again admit that for one of our first papers on the use of a gluten-free diet for autism, we did use the BSE and I have to say it performed pretty well. If I was to criticise it, I would have to say that it did not include some important features like gastrointestinal / functional bowel problems, which we were keen also to look at in that particular study.

From what I understand there are other schedules in development. My Christmas wish-list of the things I would like to see in any schedule to assess change are:

• A 5- or 7-point Likert scale/item which, like the ADOS and ADI-R offers specific descriptions for each option.
• A schedule which includes both core and peripheral symptoms (e.g. inattention, hyperactivity, impulsivity).
• A schedule which also includes items relating to more somatic features (e.g. functional bowel problems, sleeping problems, motor coordination and gait problems).
• A schedule which again like ADOS and ADI-R can be standardised across raters.

The weird thing is that all these elements are already there across the various instruments but not in one single instrument - maybe a revamp of the ADOS or ADI-R is in order? Assuming such a schedule ever appears, and some consensus on use is made (making it open-access perhaps?) it would then provide a platform for evaluating both change as a function of the natural progressions of autisms and change as a function of the various interventions.

Take it away Dave - Genius.

Diagnostic substitution and autism prevalence

I don't know if it is still part of the autism debate, but I remember a while back there was a lot of interest in whether or not diagnostic substitution was a factor in the increasing prevalence of autism spectrum conditions.
The argument went something like this: 20-odd years ago, children were diagnosed with intellectual disability (ID) even though they may have presented with either autism or autistic features. In more recent times, said children who would have been diagnosed with ID would now be classified as having autism or an autism spectrum condition as a primary diagnosis. The shift is due to either a greater awareness of autism, changing diagnostic criteria for autism or clinicians getting better and more accurately diagnosing autism.
I have to say that I always had mixed feelings about this argument. Mixed feelings because this would suggest that despite autism being included in the diagnostic manuals for quite a few years, clinicians were basically, pardon my language, either crap at diagnosing it during the 80s and 90s (perhaps into the noughties) or were so swayed by the diagnostic 'fads' of the time that they did not diagnose it. I know a few clinicians and have to say that I can't buy this being such a universal phenomena. If anything else what does this tell us about the criteria for autism being used?
On the other side of argument is the various research which has more than hinted at a reduction of ID diagnoses corresponding with an increase in autism diagnoses. It is not just in the US that this trend has been noted, but also in Canada. The 'Californa data' has been pivotal in this argument / debate.
The common consensus is that diagnostic substitution has probably contributed to the increase in autism prevalence (at least in the USA and Canada); as a percentage roughly ranging from anywhere between a quarter to about a half of cases.
I say all this because an interesting paper has emerged on PLoS ONE titled: Autism and intellectual disability are differentially related to sociodemographic background at birth. The full-text of the paper is happily available here.
You are right - the paper does not, from the title, seem like it is going to deal with the issue of diagnostic substitution, but look further, particularly at Figure 1 and there are some interesting numbers to crunch.
I think it is worthwhile stating at this point that this paper looked at Australian trends in diagnosis so we cannot really say too much other than this is what happened to Australian trends. I have talked about Australian prevalence trends in a previous post.
From Figure 1: mild-moderate ID diagnostic prevalence (without autism) by birth year peaked in 1992 and by 1999 was quite a few orders lower. Severe ID (without autism) by contrast seemed to show a quite unstable pattern throughout the whole period of study (1984-1999) with lots of peaks and troughs.
Autism (with or without ID) grew in prevalence up to 1996. At that point autism and no ID seemed to drop off (I wonder if this was a change point where Asperger syndrome became more 'fashionable' a diagnostic label to use?) whilst autism with ID continued its steady climb upwards.
The conclusion: well it is a complicated picture. It does appear as though there are some 'opposite' trends in ID and autism diagnoses but the relationship is not completely straight forward.
This is of course just my own interpretation of the figures; complete with my own biases et al. Others have their own take on the data and results. I would encourage readers to take a look at the figures themselves and draw their own conclusions on this very complicated part of the autism debate.