In case you don’t have the time to review the full recent CDC prevalence report but you’d like some more information, I’ve written a summary of the CDC report at the Autism Science Foundation blog. The CDC has provided a lot of analysis in this edition of the prevalence report.
A couple brief side points I’ll make here. Most countries have no autism prevalence studies. There is basically no prevalence information for autism in Africa or South America, for example. And, while it takes a long time between prevalence reports by the CDC, consider this paragraph:
The 14 ADDM sites that provided data for the 2008 surveillance year covered a total population of 337,093 children aged 8 years, which represented 8.4% of the U.S. population of children that age in 2008 (13). A total of 48,247 source records for 38,253 children were reviewed at education and health sources. Of these, the source records of 6,739 children met the criteria for abstraction, which was 17.5% of the total number of children whose source records were reviewed and 2% of the total population under surveillance (range: 1.0% [Alabama]–6.3% [Utah]). During clinician review, 3,820 children (57%) were confirmed as meeting the ASD surveillance case definition (range: 30% [Arkansas]–74% [North Carolina]). The number of evaluations abstracted for each child ultimately identified as having an ASD varied (median: 5; range: 3 [Florida and North Carolina]–10 [Utah].
48,247 records were reviewed. If one gives 10 minutes per document for collection and review, that’s something like three full-time man-years for that effort alone. Yeah, we’d all like the process to go faster. But we all need the report to be as accurate as possible. This is no small task.