In Wisconsin, those with low baseline prevalence have seen increase; others see leveling off
MONDAY, Oct. 25 (HealthDay News) -- In Wisconsin, the number of children with autism is increasing in school districts with low baseline prevalence, while other school districts are seeing a leveling off in their numbers, according to research published online Oct. 25 in Pediatrics.
Matthew J. Maenner, and Maureen S. Durkin, Ph.D., of the University of Wisconsin in Madison, looked at special education enrollment counts in all elementary school districts in Wisconsin from 2002 through 2008 to calculate the prevalence of children with autism. Districts were grouped into eight categories (octiles) according to their baseline prevalence.
The researchers found that, during the study period, the overall prevalence of autism increased from 4.9 to 9.0 cases per 1,000 children. Districts in the lowest octile of autism prevalence in 2002 tended to have rapid increases in prevalence over the study period, while the districts in the highest octile of autism prevalence in 2002 did not see significant increases. The highest octile/lowest octile ratio fell from 24.6 in 2002 to 1.8 in 2008.
"The prevalence of autism is expressed popularly as single point estimates for relatively large regions, such as countries or states. The findings presented here demonstrate that variability of trends within smaller areas offers additional insights into the increasing prevalence of autism in special education, and they reveal heterogeneous trends within a population," the authors write.
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