TABLE 1.
Sample Characteristics
| Autistic Disorder (n = 382) |
PDD-NOS (n = 366) |
Asperger’s Disorder (n = 221) |
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|---|---|---|---|---|---|---|
| % | Age Diagnosed Mean (SD) | % | Age Diagnosed Mean (SD) | % | Age Diagnosed Mean (SD) | |
| Total | – | 3.1 (1.7) | – | 3.9 (2.4) | – | 7.2 (3.4) |
| Demographics | ||||||
| Male | 86 | 3.0 (1.6) | 81 | 3.8 (2.3) | 89 | 7.1 (3.4) |
| Female | 14 | 3.4 (1.9) | 19 | 4.0 (2.9) | 11 | 7.3 (3.7) |
| 2–5 y of age | 40 | 2.7 (0.8) | 34 | 2.7 (0.8) | 8 | 3.9 (1.0) |
| 6–9 y of age | 26 | 2.9 (1.1) | 29 | 3.6 (1.4) | 31 | 5.4 (1.6) |
| 10–13 y of age | 22 | 3.4 (1.5) | 23 | 4.6 (2.6) | 39 | 7.5 (2.6) |
| 14–17 y of age | 9 | 3.9 (3.0) | 9 | 6.3 (4.3) | 19 | 9.8 (3.7) |
| 18–21 y of age | 3 | 6.9 (5.4) | 5 | 5.9 (3.6) | 3 | 14.6 (6.0) |
| White | 82 | 3.1 (1.6) | 82 | 3.9 (2.4) | 90 | 7.1 (3.4) |
| Black | 10 | 3.0 (2.4) | 13 | 3.9 (5.6) | 5 | 7.7 (5.0) |
| Asian/Pacific Islander | 3 | 2.8 (0.7) | 1 | 4.5 (3.7) | 2 | 8.4 (3.8) |
| Native American | 2 | 4.7 (4.8) | 2 | 3.9 (2.4) | 3 | 7.2 (3.4) |
| Latino | 3 | 3.3 (1.1) | 2 | 2.4 (0.5) | 0 | – |
| Adopted | 3 | 3.5 (1.3) | 7 | 5.2 (2.7) | 7 | 9.0 (4.1) |
| Rural | 22 | 3.5 (2.2) | 18 | 4.2 (3.1) | 24 | 8.1 (3.4) |
| Suburban | 54 | 2.9 (1.1) | 62 | 3.9 (2.3) | 58 | 7.2 (3.4) |
| Urban | 24 | 3.2 (2.2) | 20 | 3.8 (2.0) | 18 | 5.8 (3.2) |
| Income | ||||||
| Below poverty level | 15 | 3.6 (2.8) | 11 | 3.9 (3.2) | 8 | 6.1 (3.3) |
| From poverty level to 100% above | 18 | 3.2 (1.9) | 14 | 5.2 (2.9) | 22 | 8.2 (3.8) |
| >100% above | 67 | 3.0 (1.3) | 75 | 3.6 (2.2) | 70 | 7.0 (3.3) |
| Symptoms | ||||||
| Does not respond when called | 85 | 3.0 (1.6) | 77 | 3.6 (2.0) | 74 | 7.6 (3.5) |
| Self-injurious | 47 | 3.0 (1.4) | 36 | 4.0 (2.3) | 38 | 6.8 (3.0) |
| Severe language deficits | 90 | 3.0 (1.7) | 75 | 3.4 (1.8) | 22 | 5.8 (2.9) |
| Oversensitive to pain | 16 | 3.3 (2.0) | 19 | 4.9 (3.1) | 32 | 7.6 (2.9) |
| Aggressive to others | 49 | 3.0 (1.4) | 45 | 4.2 (2.6) | 55 | 6.8 (2.8) |
| Insists on sameness | 72 | 3.1 (1.6) | 68 | 3.8 (2.1) | 80 | 7.2 (3.5) |
| Lack of eye contact | 87 | 3.1 (1.7) | 84 | 3.8 (2.2) | 88 | 7.2 (3.3) |
| Sustained odd play | 72 | 3.0 (1.4) | 62 | 3.6 (1.9) | 59 | 6.9 (3.4) |
| Echolalia | 58 | 3.4 (1.9) | 65 | 3.7 (2.1) | 58 | 6.3 (2.8) |
| Hand flapping | 68 | 2.9 (1.4) | 49 | 3.6 (2.1) | 38 | 6.6 (3.0) |
| Toe walking | 52 | 3.0 (1.8) | 34 | 3.4 (1.7) | 24 | 6.0 (2.9) |
| Spins self | 41 | 3.0 (1.3) | 31 | 3.5 (1.9) | 25 | 5.7 (2.6) |
| Other clinical features | ||||||
| Mental retardation | 30 | 3.3 (2.1) | 20 | 4.5 (2.7) | 2 | 3.0 (0.9) |
| Hearing impairment | 3 | 4.1 (3.2) | 2 | 4.7 (2.1) | 1 | 6.8 (2.5) |
| Seizures | 10 | 3.2 (1.6) | 11 | 4.4 (2.9) | 4 | 8.6 (4.1) |
| Health system interactions | ||||||
| 1 primary care physician before diagnosis | 34 | 2.9 (1.0) | 39 | 3.7 (2.1) | 42 | 6.8 (3.2) |
| 2 primary care physicians before diagnosis | 39 | 3.2 (2.0) | 36 | 3.6 (2.0) | 31 | 7.2 (3.8) |
| 3 primary care physicians before diagnosis | 16 | 3.3 (2.1) | 13 | 3.9 (2.5) | 16 | 7.3 (3.4) |
| ≥4 primary care physicians before diagnosis | 11 | 3.2 (1.2) | 12 | 4.7 (3.4) | 11 | 8.1 (3.1) |
| In response to concerns about development, the primary care physician | ||||||
| Conducted developmental tests | 12 | 3.1 (1.3) | 15 | 4.6 (3.2) | 8 | 6.9 (3.2) |
| Referred to a specialist | 34 | 3.0 (1.6) | 32 | 3.8 (2.5) | 23 | 6.4 (3.8) |