Identifying developmental disability in national surveys: Addressing the knowledge gap with special education...

In the United States nearly 20% of children ages 12-17 have developmental disorders. Some attain population-based developmental milestones after a delay, or increase functioning through special education, medication, technology, or therapy. Others have severe lasting impairments. An indicator identifying those groups in surveys of adults could help shape policies to improve lives.

We hypothesized that survey histories of special education could indicate functional status levels.

Data were from the nationally representative Panel Study of Income Dynamics (1997-2017, n = 2745). With measures of diagnoses, behaviors, functional status, service use, and adult outcomes, we tested three special education groups as indicators of: (1) no impairment (no special education), (2) disorders, developmental diagnoses that adversely affect educational performance, but with development after a period of delay or only moderate disability, indicated by transfer from special education; and (3) severe lasting disability, the diagnoses combined with life-long needs for supports or services, with limitations in areas including self-care, mobility, and capacity for independent living, indicated by special education in the individual's final year of school.

Across the special education groups, from no impairment to severe lasting disability, there were trends of: increasing severe and lasting disability (respectively 4.8%, 35.6%, 76.4%); increasing special services use (13.5%, 43.1%, 83.7%); increasing severe emotional disorders (2.3%, 11.3%, 17.9%); lower percentages attaining at least an associate's degree by age 25 (42.1%, 20.7%, and 8.9%); and more chronic diseases.

Special education histories provide a useful indicator of developmental disability impairment levels in adults.