Prevalence of Autism Spectrum Disorders in a Total Population Sample

American Journal of Psychiatry
Year Published: 

A comprehensive study of school children in a region of South Korea revealed that approximately 1 in 38 children, or 2.6 percent, are on the autism spectrum. This study was the first of its kind to use total population sampling, and the findings suggest that using this technique might increase prevalence estimates in other countries. Researchers assessed more than 55,000 children between the ages of 5 and 12 living in the middle-class city of Goyang and found that two-thirds of the students with ASD were undiagnosed and had never received services. Only one third of the students with ASD were in the study's "high probability group" of 294 children enrolled in special education or listed on a disability registry. The rest of the children diagnosed with ASD were among the general population enrolled in mainstream classrooms. The authors note that if only the high probability group had been used to calculate prevalence, they would have arrived at a 0.7 percent prevalence rate -- similar to the 0.9 percent in the United States. They hypothesize that the low level of awareness about autism and the high degree of stigma surrounding the disorder in South Korea could partially explain the large number of undiagnosed children. To identify autism among children enrolled in mainstream classrooms, researchers asked parents and teachers to complete a 27-item questionnaire – children who screened positive for autism on the assessment were individually evaluated using gold-standard diagnostic methods. The study findings suggest that total population studies may be necessary to produce more accurate ASD prevalence estimates. Further work will need to be done to determine whether the South Korean findings can be generalized to other countries.

--IACC 2011 Summary of Advances in ASD Research