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.Add a Comment