New evidence about prevalence of autism
Do more parents now report that they have heard that their child has autism?
In a letter to the prestigious American Medical Association’s JAMA Pediatrics, Qian Li and collages from multiple institutions in China reported that the prevalence of autism spectrum disorders in the U.S. continued to increase in 2019 and 2020. They reported that the overall rate across the two years had grown to 3.14%, and that they were highly confident that the percentage was between 2.73 and 3.54%.
The data Li et al. used in their study was drawn from the National Health Interview Survey. That survey asks a large sample of parents, “Has a doctor or health professional ever told you that [your child] had Autism, Asperger’s disorder, pervasive developmental disorder, or autism spectrum disorder?” They used statistical methods to ensure that the results represent the country as a whole.
The average for the two years obscured their findings that for 2019, the percentage was 2.79 (95% CI: 2.34-3.24) and, for 2020 it was 3.49% (95% CI: 2.822-4.15). As in the past, parents of males were more likely than parents of females to say health professionals had told them their child had such a disorder. There were trends indicating that (a) parents of younger children were more likely than parents of older children to affirm that they had heard the diagnosis and (b) parents of Non-Hispanic Black children were less likely to have been told about such a diagnosis than parents of Non-Hispanic White childen.
Li et al. presented their data in the context of similar results from previous surveys. The accompanying image shows “box-and-whisker” diagrams for surveys from 2014 through 2020. Although there is not a continuous increase, it appears clear that the percentage of parents who report that they have had health care professionals use labels such as “autism” has increased during the seven years from 2014 through 2020.
Box-and-whisker plots provide a wealth of information. Each box and the lines connected to it describe the distribution of a metric, In this case the measure is the percentage of parents who said that a health care professional had used he term “autistic” to refer to their child. The solid dark line across the middle of the each box is the average (it may be the mean or median) for that year’s sample. The shaded area between the bottom of the box and the top of the box is where 50% of the scores fall. The bottom whisker reprsents the lowest score, and the upper whisker represents the highest score. (Researchers can set the upper and lower edges of the box and the whiskers to represent different parameters.)
Li, Q., Li, Y., Liu, B., Chen, Q., Xing, X., Xu, G., & Yang, W. (2022). Prevalence of autism spectrum disorder among children and adolescents in the United States from 2019 to 2020. JAMA Pediatrics. Published online 5 July 2022. http://doi.org/10.1001/jamapediatrics.2022.1846
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