Table 1. Trends in prevalence, demographic characteristics, and severity of children with intellectual disability, 1991–2010*.
| 1991 | 1992 | 1993 | 1994 | 1996 | 2000 | 2002 | 2004 | 2006 | 2008 | 2010 | 1991–2010 | Average annual percent change 1991–2010 | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | % | Prev | ||
| Total | n = 320 | 10.6 | n = 392 | 13.0 | n = 419 | 13.0 | n = 442 | 13.2 | n = 568 | 15.5 | n = 522 | 12.0 | n = 567 | 13.1 | n = 499 | 11.8 | n = 529 | 12.2 | n = 673 | 14.9 | N = 659 | 13.6 | N = 5590 | 13.0 | 0.35 (-0.52, 1.24) |
| Demogrpahics | |||||||||||||||||||||||||
| White non-Hispanic | 41.9 | 7.9 | 33.9 | 7.9 | 37.2 | 8.9 | 34.6 | 8.7 | 31.2 | 9.8 | 24.1 | 6.8 | 26.5 | 8.8 | 22.0 | 6.8 | 24.0 | 8.4 | 19.5 | 8.6 | 23.2 | 9.6 | 27.7 | 8.4 | 0.12 (-0.90, 1.16) |
| Black non-Hispanic | 55.9 | 15.7 | 62.2 | 21.1 | 59.9 | 20.0 | 60.2 | 19.8 | 62.0 | 22.7 | 62.3 | 16.5 | 60.0 | 17.0 | 60.9 | 15.8 | 59.4 | 15.6 | 56.9 | 18.7 | 53.0 | 16.8 | 59.2 | 17.9 | -0.95 (-1.92, 0.03) |
| Hispanic | nr | nr | 2.3 | 9.4 | nr | nr | 3.6 | 12.3 | 3.5 | 15.6 | 6.9 | 10.5 | 7.9 | 10.9 | 10.2 | 11.3 | 12.3 | 12.2 | 14.1 | 14.4 | 15.3 | 11.7 | 8.0 | 11.7 | 2.00 (0.15, 3.87) |
| Asian non-Hispanic | nr | nr | 1.5 | 6.9 | 1.7 | 7.7 | 1.6 | 7.0 | 2.6 | 12.5 | 3.3 | 9.3 | 3.2 | 9.4 | 3.4 | 7.2 | 2.5 | 4.9 | 5.6 | 14.1 | 5.0 | 10.4 | 3.1 | 8.9 | 2.20 (-1.22, 5.76) |
| Male | 57.8 | 12.1 | 58.2 | 14.9 | 62.1 | 15.9 | 60.2 | 15.7 | 62.3 | 19.1 | 59.0 | 14.0 | 64.4 | 16.5 | 63.3 | 14.8 | 65.0 | 15.6 | 71.0 | 20.5 | 69.0 | 18.6 | 63.7 | 16.3 | 1.19 (1.0, 2.30) |
| Female | 42.2 | 9.1 | 41.8 | 11.0 | 37.9 | 10.0 | 39.8 | 10.7 | 37.7 | 11.8 | 41.0 | 9.9 | 35.6 | 9.6 | 36.7 | 8.7 | 35.0 | 8.7 | 29.0 | 8.9 | 31.0 | 8.5 | 36.3 | 9.6 | -1.18 (-1.84, -0.51) |
| Level of severity | |||||||||||||||||||||||||
| Mild (IQ 50–70) | 57.8 | 6.2 | 68.6 | 8.9 | 66.1 | 8.6 | 69.5 | 9.2 | 66.2 | 10.2 | 63.2 | 7.6 | 60.5 | 7.9 | 59.1 | 7.0 | 60.5 | 7.4 | 60.0 | 8.9 | 69.3 | 9.4 | 63.7 | 8.3 | 0.10 (-1.14, 1.37) |
| Moderate to Profound (IQ <50) | 40.9 | 4.4 | 30.9 | 4.0 | 32.7 | 4.2 | 29.0 | 3.8 | 28.2 | 4.4 | 32.8 | 3.9 | 35.3 | 4.6 | 31.3 | 3.7 | 32.9 | 4.0 | 35.4 | 5.3 | 27.9 | 3.8 | 32.2 | 4.2 | 0.18 (-0.80, 1.17) |
| ID NOS | nr | nr | nr | nr | 1.2 | 0.2 | 1.6 | 0.2 | 5.6 | 0.9 | 4.0 | 0.5 | 4.2 | 0.6 | 9.6 | 1.1 | 6.6 | 0.8 | 4.6 | 0.7 | 2.7 | 0.4 | 4.1 | 0.5 | 7.21 (0.35, 14.5) |
*Proportions and prevalence estimates with numerators <5 children are suppressed due to small sample sizes. Trend analyses reflect weighted prevalence for surveillance years with n<5 children and the subsequent surveillance year (e.g., trend for Hispanic children with ID combined 1991–1992 numerators and denominators for the first time period).