19904
Utility of Documented Special Education Exceptionality Categories for ASD Prevalence Estimation Among Children Identified with ASD in the ADDM Network
Special education exceptionality (SEE) is a label indicating how a student qualifies for special education services in US public schools. The count of children in specific SEEs has been used to estimate disability prevalence. In such systems, disability prevalence by child’s race/ethnicity and sex may be influenced by differential ascertainment.
Objectives: To examine SEE classification trends among eight-year-old children with autism spectrum disorders (ASD) over time and across child sex and race/ethnicity subgroups to explore potential utility of SEE categories to estimate ASD prevalence for these population subgroups.
Methods: The Autism and Developmental Disabilities Monitoring (ADDM) Network conducts multi-source population-based surveillance of ASD prevalence in eight-year-old children. Case status is determined by clinician review of education and developmental records for children with variety of disabilities. This study examined data from 2002, 2006, 2008, and 2010 surveillance years (SY). Children were included if they were identified as having ASD following clinician review of health and education data from one of nine sites that participated in ADDM in at least three of four SYs (N=9110). Mixed effects logistic regression models were fit with SY as a fixed effect and site as a random intercept to adjust for underlying site-related characteristics. To evaluate temporal trend, site-specific odds ratios of SEE were estimated for SY 2006, 2008, or 2010 versus the reference SY 2002. Significant Wald tests comparing odds ratios from each SY indicated difference. Additional models were developed, one with sex and a sex by SY interaction term, and another with race/ethnicity (white non-Hispanic, black non-Hispanic, or Hispanic) and a race/ethnicity by SY interaction term.
Results:
In this sample of children with ADDM identified ASD, “autism” was the most common SEE (range: 51.7 to 56.8% over SYs) and use increased 10% from 2002-2010 (P=0.003). “Other health impairment” and “developmental delay” SEEs were less common, but also increased significantly from 2002-2010 (29.1% increase to 9.2% in 2010 and 1800% increase to 6.3% in 2010, respectively). The largest significant decreases were seen among “multiple disabilities” and “intellectual disability” SEEs (both by 52% from 2002 to 2010, P<.001).
Among males, assignment of “autism” SEE ranged from 52.8% to 58.0% over SYs (P=0.01) and among females it ranged from 47.1% to 52.2% (P=0.07). There was no significant interaction between sex and SY (P=0.7).
Assignment of “autism” SEE ranged from 53.7% to 57.1% in both white and black non-Hispanic children and did not change significantly over SYs. Among Hispanic children, assignment of “autism” increased from 38.5% to 55.7% (P<0.001). There was significant interaction between race/ethnicity and SY (P<0.001)
Conclusions:
Although autism exceptionality is the most common SEE among children with ASD identified by ADDM, regardless of sex or race/ethnicity, almost half of children with ASD do not have autism as their primary SEE. An increase in the proportion of Hispanic children with ASD identified by ADDM who have autism SEE may indicate decreasing disparity in identification of ASD by race/ethnicity for special education purposes. Estimating ASD prevalence using autism SEE underestimates ASD prevalence and should be done with caution. 