Table 3. Prevalence of Autism Spectrum Disorders Among Children With Down Syndrome Aged 2 to 11 Years, Overall and By Demographic and Cognitive Characteristics.
| Characteristic | Autistic Disorder Weighted Percent (95% CI) | Pervasive Developmental Disorder-Not Otherwise Specified Weighted Percent (95% CI) | Total Autism Spectrum Disorder Weighted Percent (95% CI) |
|---|---|---|---|
| Total | 6.4 (2.6–11.6) | 11.8 (7.0–18.4) | 18.2 (9.7–26.8) |
| Gender | |||
| Male | 6.8 (0.2–13.5) | 17.1 (9.9–26.1) | 23.9 (11.9–35.9) |
| Female | 5.8 (1.5–15.8) | 2.9 (0.0–8.6) | 8.7 (0.0–18.4) |
| Race | |||
| White Non-Hispanic | 6.8 (0.8–12.7) | 12.9 (0.0–21.1) | 19.7 (9.9–29.4) |
| All other races | 5.5 (0.0–16.4) | 8.4 (0.0–24.3) | 13.9 (0.0–32.4) |
| Ethnicity | |||
| Hispanic | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) |
| Not Hispanic | 7.5 (1.5–13.5) | 13.8 (5.5–22.2) | 21.3 (11.5–31.2) |
| Birth year | |||
| 1996–1999 | 9.5 (3.1–22.5) | 9.5 (3.1–22.5) | 19.0 (1.3–36.7) |
| 2000–2001 | 3.7 (0.0–11.0) | 14.9 (0.0–30.8) | 18.5 (1.5–35.5) |
| 2002 | 7.5 (0.0–17.9) | 7.5 (0.0–17.9) | 15.0 (0.1–29.3) |
| 2003 | 5.4 (1.1–22.0) | 16.2 (0.0–33.6) | 21.6 (1.2–41.2) |
| Severity of cognitive impairmenta | |||
| Mild | 0.0 (0.0–10.9) | 9.1 (0.0–19.4) | 9.1 (0.0–19.4) |
| Moderate | 0.0 (0.0–20.6) | 19.9 (1.4–38.3) | 19.9 (1.4–38.3) |
| Severe | 27.8 (7.8–47.8) | 16.2 (0.0–33.8) | 44.1 (21.1–67.2) |
a
Missing data for 12 children who did not complete cognitive testing.