One of the most intriguing scenarios to pop up from the so-called autism epidemic happened in Minnesota in the US. It was noted that there were what seemed to be disproportionately high numbers of second generation Somali children in Minnesotan schoolrooms. Of course, this was immediately latched on to by the usual suspects, despite the caution issues by health authorities that until proper epidemiological studies had been done it would be impossible to say whether this really was a cluster worth investigation or just a coincidence.
On the 31st March, the Minnesota Dept Health released the study. Its a fairly substantial read. One thing immediately struck me about this:
Administrative prevalence of Somali children, ages 3 and 4, who participated in the MPS ECSE ASD programs was significantly higher than for children of other races or ethnic backgrounds
OK so this is what the families were saying. But there’s an extreme note of caution that should be noted here. This is basically CDDS all over again. Just like some believed that an increasing number of reports to CDDS meant that there was an autism epidemic and just as CDDS said there reports really shouldn’t be used to study these things, MDH are also saying:
Because of the study’s limitations, it is not proof that more Somali children have autism than other children…
This is a vital point. Back in 2005, James Laidler made the clear point that Department of Education data on autism are not reliable for tracking autism prevalence.
Sadly, the new Age of Autism editor, Abdulkadir Khalif, either misunderstood or elected to ignore this issue when he said:
It was obvious from the numbers that the issue of prevalence has finally been settled, and that there definitely is a cluster of autism in Minneapolis
It is clear from the report that Khalif has grossly overstated the case. Firstly, the issue of prevalence is far from settled. MDH seem to be solely using educational data which, as pointed out by Laidler, is not reliable for tracking autism prevalence. Indeed the phrase ‘administrative prevalence’ used by MDH reflects this. ‘Administrative prevalence’ refers solely to numbers of kids in educational programs. This is a clear distinction from ‘prevalence’ which is the proportion of individuals in a population who suffer from a defined disorder. Using only educational data gives a distorted picture.
As has been shown, the USDE data on autism are at odds with studies of autism prevalence, largely because the criteria used by the school districts (the source of the USDE data) to categorize children as autistic are neither rigorous nor consistent. They are inconsistent over time, as are the medical criteria, and are inconsistent from region to region. The USDE data are not reliable for tracking the prevalence of autism, and they in fact never were meant to fill this need.
Secondly Khalif uses the word ‘cluster’ whereas the MDH report does not use it at all. And it is not a word that should be used in such a throwaway fashion – it has a distinct epidemiological meaning.
So clearly, contrary to Khalif’s assertion that the issue of prevalence has been settled, it has not. Contrary to his statement that there is a cluster, there has been no such epidemiological assessment or statement.
Here are some more quotes from the MNH report that Abdulkadir Khalif either chose to ignore or never actually read:
The fact that a child is participating in an ASD early childhood program is an indicator of educational need, but that child may or may not have a medically diagnosed ASD.
Further, Minnesota’s public school open enrollment policy allows children to attend special education programs in school districts where they are not residents. This raised the question of whether participation rates for Somali children might appear higher than the participation rates for non-Somali children because of an influx of Somali children who are not residents of the Minneapolis school district attending MPS ECSE programs for ASD.
Data on variability of ASD prevalence by race, ethnicity, and SES is limited and inconclusive, and apparent differences between racial and ethnic populations may largely be due to differences in case finding and service provision.
Across all assumptions and ASD program types, administrative ASD prevalence estimates for Somali children were uniformly higher than the U.S. parental reported ASD prevalence, but most of the 95% confidence intervals corresponding to the administrative prevalence estimates for Somali children contained the value of the U.S. parental reported ASD prevalence estimate – suggesting that the 2005-2006 administrative ASD prevalence for Somali children might be no different from what would be expected in the U.S. population of children ages 3 and 4 based on parental report.
So what does this mean?
It means that there are no firm answers and that Khalif is simply wrong to assert that there are.
Its always been one of the great puzzles to me that a section of (mostly) parents who demand accurate answers fast cannot seem to understand that there are no accurate answers until the science – proper science – has been done. And that takes time. What legacy do these parents want to leave the autism community? Fast inaccurate mistakes? Or well planned and rigorous science that helps build the growing knowledge we already have?