TABLE 1

Prevalence of ADHD According to Environmental Exposure, Sociodemographic Characteristics, and Medical Factors

CharacteristicNo. With ADHDcWeighted Proportion With ADHD, Estimate (95% CI), %Pb
Total2228.7 (7.3–10.1)
Blood lead level<.001
    First tertile (0.2–0.8 μg/dL)435.2 (3.4–7.0)
    Second tertile (0.9–1.3 μg/dL)639.1 (5.8–12.5)
    Third tertile (>1.3 μg/dL)10713.6 (11.0–16.2)
Prenatal tobacco exposure<.001
    Yes6316.8 (12.3–21.4)
    No1526.6 (5.2–8.0)
Household smoke exposurec.01
    First tertile (0.2–0.027 ng/mL)477.0 (4.1–9.9)
    Second tertile (0.028–0.202 ng/mL)708.3 (5.5–11.2)
    Third tertile (0.203–10 ng/mL)8812.4 (9.8–15.1)
Gender<.001
    Male14111.8 (9.8–13.8)
    Female815.4 (4.2–6.6)
Age.08
    8–11 y11910.0 (7.9–12.1)
    12–15 y1037.5 (5.5–9.4)
Race/ethnicity.06
    Mexican American456.0 (4.3–7.8)
    Non-Hispanic black768.7 (6.4–10.9)
    Other race/ethnicity175.2 (1.8–8.7)
    Non-Hispanic white849.8 (7.4–12.1)
Income/poverty ratio
    First quintile (0–0.93)6911.0 (7.9–14.0).19
    Second quintile (0.94–1.70)469.6 (4.7–14.5)
    Third quintile (1.71–2.75)408.5 (4.6–12.5)
    Fourth quintile (2.76–4.24)349.0 (5.5–12.6)
    Fifth quintile (>4.24)286.4 (3.6–9.1)
Attended preschool.01
    Yes1719.5 (7.7–11.3)
    No516.4 (4.8–8.0)
Mother's age at child's birth.12
    ≤18 y2813.1 (7.1–19.1)
    >18 y1948.4 (7.0–9.7)
NICU admission.43
    Yes3210.2 (6.1–14.2)
    No1868.4 (6.9–9.9)
Birth weight.18
    <2.5 kg2314.3 (6.6–21.9)
    ≥2.5 kg1978.3 (6.6–9.9)
  • a Subjects with ADHD met DSM-IV criteria for any ADHD subtype.

  • b For between-group comparison of prevalence rates in χ2 analyses.

  • c Assessed through serum cotinine levels.