TABLE 1.

Sample Characteristics

Autistic Disorder (n = 382)PDD-NOS (n = 366)Asperger's Disorder (n = 221)
%Age Diagnosed Mean (SD)%Age Diagnosed Mean (SD)%Age Diagnosed Mean (SD)
Total3.1 (1.7)3.9 (2.4)7.2 (3.4)
Demographics
    Male863.0 (1.6)813.8 (2.3)897.1 (3.4)
    Female143.4 (1.9)194.0 (2.9)117.3 (3.7)
    2–5 y of age402.7 (0.8)342.7 (0.8)83.9 (1.0)
    6–9 y of age262.9 (1.1)293.6 (1.4)315.4 (1.6)
    10–13 y of age223.4 (1.5)234.6 (2.6)397.5 (2.6)
    14–17 y of age93.9 (3.0)96.3 (4.3)199.8 (3.7)
    18–21 y of age36.9 (5.4)55.9 (3.6)314.6 (6.0)
    White823.1 (1.6)823.9 (2.4)907.1 (3.4)
    Black103.0 (2.4)133.9 (5.6)57.7 (5.0)
    Asian/Pacific Islander32.8 (0.7)14.5 (3.7)28.4 (3.8)
    Native American24.7 (4.8)23.9 (2.4)37.2 (3.4)
    Latino33.3 (1.1)22.4 (0.5)0
    Adopted33.5 (1.3)75.2 (2.7)79.0 (4.1)
    Rural223.5 (2.2)184.2 (3.1)248.1 (3.4)
    Suburban542.9 (1.1)623.9 (2.3)587.2 (3.4)
    Urban243.2 (2.2)203.8 (2.0)185.8 (3.2)
Income
    Below poverty level153.6 (2.8)113.9 (3.2)86.1 (3.3)
    From poverty level to 100% above183.2 (1.9)145.2 (2.9)228.2 (3.8)
    >100% above673.0 (1.3)753.6 (2.2)707.0 (3.3)
Symptoms
    Does not respond when called853.0 (1.6)773.6 (2.0)747.6 (3.5)
    Self-injurious473.0 (1.4)364.0 (2.3)386.8 (3.0)
    Severe language deficits903.0 (1.7)753.4 (1.8)225.8 (2.9)
    Oversensitive to pain163.3 (2.0)194.9 (3.1)327.6 (2.9)
    Aggressive to others493.0 (1.4)454.2 (2.6)556.8 (2.8)
    Insists on sameness723.1 (1.6)683.8 (2.1)807.2 (3.5)
    Lack of eye contact873.1 (1.7)843.8 (2.2)887.2 (3.3)
    Sustained odd play723.0 (1.4)623.6 (1.9)596.9 (3.4)
    Echolalia583.4 (1.9)653.7 (2.1)586.3 (2.8)
    Hand flapping682.9 (1.4)493.6 (2.1)386.6 (3.0)
    Toe walking523.0 (1.8)343.4 (1.7)246.0 (2.9)
    Spins self413.0 (1.3)313.5 (1.9)255.7 (2.6)
Other clinical features
    Mental retardation303.3 (2.1)204.5 (2.7)23.0 (0.9)
    Hearing impairment34.1 (3.2)24.7 (2.1)16.8 (2.5)
    Seizures103.2 (1.6)114.4 (2.9)48.6 (4.1)
Health system interactions
    1 primary care physician before diagnosis342.9 (1.0)393.7 (2.1)426.8 (3.2)
    2 primary care physicians before diagnosis393.2 (2.0)363.6 (2.0)317.2 (3.8)
    3 primary care physicians before diagnosis163.3 (2.1)133.9 (2.5)167.3 (3.4)
    ≥4 primary care physicians before diagnosis113.2 (1.2)124.7 (3.4)118.1 (3.1)
    In response to concerns about development, the primary care physician
    Conducted developmental tests123.1 (1.3)154.6 (3.2)86.9 (3.2)
    Referred to a specialist343.0 (1.6)323.8 (2.5)236.4 (3.8)