Willard wrote:
How about this:
Families with higher income levels are more likely to be able to afford the diagnostic process than poor folk.
If you have no health insurance and are barely surviving from month to month, you're more likely to die of cancer than a rich person who develops cancer - because they're more likely to get regular checkups, discover it early and get treatment. If you're poor you probably won't know you're sick until you're already eaten up with it.
KaiG wrote:
Also, maybe the less well-off you are, the less likely you are to be diagnosed.
This issue is treated in the article:
Quote:
Autism spectrum disorders (ASDs) have long been known to show this pattern, at least in some countries, but this has often been thought to be a product of diagnostic ascertainment bias. Maybe richer and better-educated parents are more likely to have access to services that can diagnose autism. This is a serious issue because autism often goes undiagnosed and diagnosis is rarely clear-cut.
An important new PLoS paper from Wisconsin's Durkin et al suggests that, while ascertainment bias does happen, it doesn't explain the whole effect in the USA: richer American families really do have more autism than poorer ones. The authors made use of the ADDM Network which covers about 550,000 8 year old children from several sites across the USA. (This paper also blogged about here at C6-H12-O6 blog.)
ADDM attempts to count the number of children with autism based on
abstracted data from records of multiple educational and medical sources to determine the number of children who appear to meet the ASD case definition, regardless of pre-existing diagnosis. Clinicians determine whether the ASD case definition is met by reviewing a compiled record of all relevant abstracted data.
Basically, this allowed them to detect autism even in kids who haven't got a formal diagnosis, based on reports of behavioural problems at school etc indicative of autism. Clearly, this is going to underestimate autism somewhat, because some autistic kids do well at school and don't cause any alarm bells, but it has the advantage of reducing ascertainment bias.
What happened? The overall prevalence of autism was 0.6%. This is a lot lower than recent estimates in 5-9 year olds in the UK (1.5%), but the UK estimates used an even more detailed screening technique which was less likely to leave kids undetected.
(...)
The headline result: autism was more common in kids of richer parents. This held true within all ethnic groups: richer African-American or Hispanic parents were more likely to have autistic children compared to poorer people of the same ethnicity. So it wasn't a product of ethnic disparities.
Crucially, the pattern held true in children who had never been diagnosed with autism, although the effects of wealth were quite a bit smaller: