Posts Tagged ‘ rate of ASD ’

“1 in 68″: The New Data On Autism Spectrum Disorder

Friday, March 28th, 2014

It is now estimated that 1 in 68 children are diagnosed with Autism Spectrum Disorder (ASD), based on a report issued by the Centers for Disease Control and Prevention. This detailed CDC report deserves a close look as there are a number of important findings on the prevalence of ASD and factors that influence evaluation and diagnosis.

THE RATE KEEPS INCREASING: As described by the CDC, the new estimate is 30% higher than the prior estimate made just 2 years ago (1 in 88). The estimated prevalence of ASD has gone up tremendously in the last decade, and it is assumed that improved recognition and diagnosis is the primary factor. The implication here is that we have underestimated the true rate of ASD and as such the new data suggest an urgency in mobilizing resources to understand the causes and accelerate the delivery of interventions (see, for example, the reaction from Autism Speaks to the new estimate).

SEX OF CHILD MATTERS: ASD has always been more prevalent in boys. The new data continue to support that, as 1 in 42 boys in the study received a diagnosis, as compared to 1 in 189 girls. The reasons for this sex difference are still not well understood. But it’s clear that boys in particular are especially likely to be diagnosed with ASD – 1 in 42 is a very high prevalence for any disorder. So anticipate increased efforts at screening for ASD by pediatricians, especially for boys. And it is noted  that ASD should be screened for in girls with more intensity as well, as 1 in 189 is a high prevalence for a disorder.

ETHNICITY MATTERS: While the rates of ASD continue to go up, it is diagnosed more frequently in white, non-Hispanic children. Non-Hispanic white children are 30 times more likely to receive a diagnosis as compared to non-Hispanic black children, and nearly 50% more likely to be diagnosed than Hispanic children. Evaluative and diagnostic efforts need to increase for children in these ethnic groups.

ALL LEVELS OF COGNITIVE FUNCTIONING ARE AFFECTED: Nearly half (46%) of the diagnosed cases in the study had cognitive abilities in the average or above average range. This is potentially one factor that has increased the estimated prevalence over time, as there is more recognition of symptoms of ASD without cognitive/intellectual impairment. Level of cognitive functioning is important clinically in terms of managing other potential conditions and planning interventions – but it’s clear that ASD is being diagnosed across all levels of functioning.

ASD IS STILL DIAGNOSED LATER THAN IT COULD BE: Although recognition of ASD has certainly increased over the last decade, the evaluative and diagnostic efforts are still being done later rather than sooner. The CDC suggests that less than 50% of the diagnosed cases were evaluated before age 3, and that the majority of diagnoses were made after age 4. Reliable screenings of ASD can be made by 2 years of age, and it is imperative that early detection is encouraged, as there are interventions that can begin at these earlier ages. So while detection of ASD has improved over time, we need to see evaluations done at younger ages to ensure that children with ASD receive interventions as early as possible.

WILL THE RATES CONTINUE TO RISE?: This question is raised because of the change in diagnostic criteria offered by the DSM-5, which was introduced in May 2013. Note that the current study collected data in 2010, using the prior version of the DSM (the DSM IV-R). There has been much speculation that the prevalence of ASD will decline given the new criteria. However, we are years away from getting the answer to that question, given the amount of time that it takes to mobilize these intensive data collection efforts. But it’s something to keep in mind for the future.

WHAT ARE THE MOST IMPORTANT IMPLICATIONS OF THE “1 in 68″ STUDY?: Clearly, the need for earlier detection is key – we can’t confuse the increasing recognition with early detection. More vigilant efforts need to be applied to evaluate children in every ethnic group. And while the rate of ASD in girls is much less than that for boys, keep in mind that “1 in 189″ is still a very high prevalence, so efforts to detect ASD in girls should also be intensified. For parents, the most important point is to be aware of early signs of ASD, and to work collaboratively with your pediatrician to monitor your child’s early development and seek out further evaluation if necessary as young as possible.

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Do 1 in 50 Kids Have Autism Spectrum Disorder?

Wednesday, March 20th, 2013

The Centers for Disease Control (CDC) have released a report that suggests 1 in 50 kids suffer from autism spectrum disorder (ASD). This is indeed the number they found in their study of over 100,000 families. But that said, it’s difficult to draw firm conclusions on this finding. Here are a few key points to consider: 

1) One of the reasons that the rate of ASD has increased from the prior estimate of 1 in 88 kids is that, in this new study, data on older kids were collected. The prior estimate derived from sampling families who had an 8 year old child. The new research reached out to families with kids between 6-17 years of age. Thus one of the suggestions is that this newer estimate is higher because older kids with more mild symptoms were more likely to be represented in the sample. In this sense, the new data are more informative.

2) That said, it should be noted that the participation rate in the new study was quite low – only 23% of the families contacted participated in the survey. The authors suggest that this sample was not biased (based on statistical modeling used). However, it’s worth noting that prior estimates were based on sampling that resulted in participation rates closer to 50%. The issue – that isn’t resolved – is the extent to which families who have a child with ASD were more likely to participate – or put another way, families who don’t have kids with ASD may not have been motivated to participate. Bottom line, this participation rate is a concern.

3) The new study asked parents (or guardians) directly if they have been told (by a practitioner) that a child in the home (in the targeted age range) has ASD and also if the child currently has ASD. The authors suggest that this is an important strategy because not every child receives services and hence service-based estimates may be biased. But it’s also the case that only asking a parent/guardian these particular questions does not give a complete picture (for example, a child may have been misdiagnosed by a practitioner in either direction). So this sampling strategy is a mixed bag – there are both advantages and disadvantages to it. Of course, the gold standard would be to do a diagnostic assessment of all the kids – but something of this magnitude is typically not feasible for pragmatic reasons (it would be a huge scientific undertaking).

Taken together, we see that this study had strengths, weaknesses, and some mixed elements to it. Conducting a study of this magnitude is very difficult and as such the data should not be dismissed. But it’s tough to say if the new estimate is the “real” one or just another statistical estimate that is higher than previously thought.

We do, however, know three things for sure. First, whatever the true population estimate may be, ASD undoubtedly affects a profound number of youth. Second, it will be critical to evaluate how the new diagnostic criteria in the upcoming DSM 5 will impact these estimates – especially since there have been suggestions that at least 10% of kids currently diagnosed with ASD will no longer meet diagnostic criteria. And third, the key for any child who is diagnosed with ASD is to get intervention as early as possible, especially given some of the latest encouraging findings.

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