It’s widely believed that early intervention is crucial for long-term prognosis in autism and that the earlier the intervention begins the better. Getting in early, of course, requires that autistic children are identified at a young age. But even for more severe forms of autism, children are rarely diagnosed before three to four years of age. With this in mind, the American Academy of Pediatrics has recommended screening all toddlers for autism.
However, writing in next July’s issue of Pediatrics (the academy’s own journal), Mona Al Qabandi and colleagues argue against routine population-based screening for autism. Chief amongst their objections is that existing screening tools are simply not up to the task. Most of these screens involve a questionnaire given to parents, sometimes augmented with a brief phone interview. But they all have their problems. Some are insensitive, missing a large number of kids who go on to get an ASD diagnosis further down the line. Others are sensitive but not specific, hoovering up all kinds of kids, many of whom don’t have autism, and may not have any kind of developmental problems at all.
Al Qabandi et al. conclude that “none of the autism screening tests currently available has been shown to be able to fulfill the properties of accuracy… in a population-wide screening program”.
Similar conclusions were reached in an earlier review by Josephine Barbaro and Cheryl Dissanayake at the Olga Tennison Autism Research Centre in Melbourne. So they tried a different approach. Rather than relying on parental questionnaires, they set up a 'surveillance program', training community nurses to spot the signs of autism during regular infant health checks.
Each nurse attended a short two-and-a-half-hour workshop in which they were shown how to complete the screen. They were given a checklist with key behaviours to monitor, depending on the child’s age, and were trained how to score each item as either typical, atypical, or absent. For instance, the item for “eye contact” read as follows:
"Has the child spontaneously made eye contact with you during the session? If not, interact with the child to elicit eye contact. Does s/he make eye contact with you?"From an initial sample of almost 21 thousand children, 216 were identified as “at risk” of ASD by 24 months of age. Of these, 110 completed further assessment, including the ADOS and ADI-R. 89 of these kids received an ASD diagnosis, giving the surveillance program a positive predictive value of 81%. Of the remaining 21 children, all but one had developmental language disorders.
Calculating the
To get a more accurate indication of sensitivity, however, the researchers will have to wait until the children enter school. Only then will they be able to work out how many children end up with an ASD diagnosis but weren’t picked up by the
While it’s still early days, the Melbourne study suggests that population-wide screening for autism is possible, at least in areas that already have comprehensive regular child health checks.
References:
Barbaro, J., & Dissanayake, C. (2010). Prospective Identification of Autism Spectrum Disorders in Infancy and Toddlerhood Using Developmental Surveillance: The Social Attention and Communication Study Journal of Developmental & Behavioral Pediatrics, 31 (5), 376-385 DOI: 10.1097/DBP.0b013e3181df7f3c
Al-Qabandi M, Gorter JW, & Rosenbaum P (2011). Early Autism Detection: Are We Ready for Routine Screening? Pediatrics PMID: 21669896
Links:
Olga Tennison Autism Research Centre
Further reading:
Imagine screening for "gayism". Just a thought.
ReplyDeleteIf you find me offensive, just tell me and I'll go crawl back into my corner. You have to tell me, though, because I always think I'm right. Gotta knock me off my high horse, as dad would say.
Not offensive. I just don't understand the analogy!
ReplyDeleteI think I understand the gayism analogy - the conception is that the disabling aspects of ASD are just social constructs and the ASD person is a minority 'type' whose behaviours are considered 'deviant' by the majority.
ReplyDeleteThis is an important consideration, however it is limited in application because it seems pretty clear that there are individuals, who would be described as being affected by ASD, whose disablement and distress appears endemic, rather than being the result of social constructs. In that case identification and intervention would be valid, at least insofar as the reduction of disabling and distressing symptomology was the purpose of any intervention.
Nevertheless, the voice of ASD people needs to be heard more substantively in discussions about 'treatment', far too often the discourse is prescribed by advocates (parents) and parents.
A correction...the reason why the Social Attention and Communication Study undertaken in Melbourne and reported on here was successful was that it did not use a SCREEN but rather employed a DEVELOPMENTAL SURVEILLANCE approach where the infants/toddlers were rountinely monitored at their health checks. Thus a baby who was monitored and did not present as 'at risk' at one age (eg 12 months) was monitored again at the next health check (eg 18 months)...so this approach acknowledges the fact that ASDs have a variable onset...hence the good positive predictive value. One off SCREENS are not successful for this very reason.
ReplyDeleteHi Cheryl
ReplyDeleteThanks for the comment. I've edited the post in the couple of places where I've said "screen" to refer to your study. I was taking "screen" to refer to any form of check that was targeted at the whole population (which would include your study).
As a follow up to your comment though, I wonder if you can be sure that it was the multiple "screening" that was important. Put another way, would a single screen at 24 months not have done just as good a job? Obviously, conducting earlier screens does allow you to identify a proportion of the kids at a younger age, but that's a different issue.
Yes, we feel that 24-months is too late. Would the results in terms of PPV have been the same if we only monitored at 24-months? May be. In a previous study we did on early signs in infancy and toddlerhood (Clifford & Dissanayake, 2008), we found a dropping off of skills between 18- and 24-months. Thus if we can identify children and intervene prior to this drop off, their developmental outcomes are likely to be even better.
ReplyDeleteSo it seems that by 24 months, you'd picked up on a good proportion of ASD kids. At 18 months, the sensitivity is much less impressive, but presumably these are the more severe cases, where there's the most pressing need for intervention. Is that the sense you get?
ReplyDeleteI think that even the children who were not identified until 24 months would be in need of intervention as much as those who were identified at 18 months. We can't know for sure if these children were not identified at 12 or 18 months because their symptoms were less severe. Yes this would be the case for some children, but for others, it could be that nurses may not have been as confident to refer, parents were less likely to take up the referral and wait until the next consult etc. Therefore I would argue that SACS just done at 24 months most likely wouldn't have produced the same sensitivity, as I feel there would have already been some ground work in the previous consults, some red flags identified, some discussions with parents, and so when the 24 month visit comes around, parents would be much more receptive to a referral because of the previous health checks. Tools and procedures to identify autism early could be the most sensitive they could possibly be, but if parents do not take up the referral, then their accuracy is redundant. Thus, repeated monitoring, discussions, and referrals should all be part of a good tool or method to identify autism early.
ReplyDeleteI think this would help in stopping the delay of diagnosis because a professional doesn't want to label. A label can get services which could include means of teaching a way for the child to communicate. I am a professional in the field and so wanted to believe everyone telling me oh he's just a boy he'll talk later and oh he's just a big baby so it's harder for him to pull himself up. At 18 months he tested at low end of normal for speech. There were issues noted in the way he walked but everything was put down as a delay. At 3 he was diagnosed developmentally delayed, too late to receive early intervention (free of charge). At 4 he was kicked out of preschool for his delays. Finally at 5 he was given the asd diagnosis. I can't say for sure whether my son would have been picked up in the study. One of the things that kept throwing people off was that he has great eye contact... when he wants to.
ReplyDeleteKnowing how much I have taught my son and how hard I worked where would he have been if there was a whole team working with him?
I don't understand why it's so important to screen for *autism*.
ReplyDeleteGiven that interventions address a specific developmental issue, such as eye contact, reciprocity, use of language etc, wouldn't it make more sense to look for any developmental issues that appear problematic and provide appropriate support?
That way, all toddlers with developmental deficits would benefit, regardless of what category they were eventually allocated to.
I think Sue Gerrard has it right. The diagnostic checklists for 'autism' are all subjective with respect to where is the 'cutoff' score that distuinguishes 'autism' from other developmental problems. There is no resaon why toddlers should not be screened as early as possible for any developmental problem and referred to appropriate evidence based early intervention programs.
ReplyDeleteJon, you might be interested in a new study that may be relevant to this discussion. Researchers from Griffith University in Australia found there are no natural boundaries between disorders or between disorders and normality.
Lots of good research coming from the UK and Australia which unfortunatly is rare in the US.
http://www.ncbi.nlm.nih.gov/pubmed/21705192