Childhood Blood Lead Levels and Symptoms of Attention Deficit Hyperactivity Disorder (ADHD): A Cross-Sectional Study of Mexican Children

http://dx.doi.org/10.1289/ehp.1510067



Table 2. Adjusteda associations between a 1-μg/dL increase in blood lead and CRS-R outcomes in children 6–13 years from segmented regressions or least-square regressions using the imputed data set (n = 578).
Outcome Breakpointb
(95% CI) (μg/dL)
Slope1
(95% CI)c
p Slope2
(95% CI)
p
aAll models were adjusted for maternal marital status, age, educational years, SES, and ever smoked during pregnancy, and the child’s age at behavioral testing, sex, and birth weight. bBreakpoints were optimized from iterations in piecewise regressions using the imputed dataset. cBiological meaningful breakpoints were not found in the models marked “NA”; the estimate shown reflects single slope for the entire range of the exposure distribution estimated using ordinary least-square regressions.
CRS-R
Cognitive Problem/Inattention NA –0.03 (–0.3, 0.2) 0.85 NA NA
Hyperactivity 5.0 (2.4, 7.6) 1.2 (0.3, 2.0) 0.01 –0.3 (–0.8, 0.2) 0.26
ADHD Index NA 0.02 (–0.2, 0.3) 0.86 NA NA
CGI Restless-Impulsive 5.1 (2.7, 7.5) 1.2 (0.3, 2.0) 0.007 –0.3 (–0.7, 0.1) 0.15
CRS-R DSM-IV
Inattentive NA 0 (–0.3, 0.3) 0.98 NA NA
Hyperactive-Impulsive 5.2 (2.5, 7.8) 1.1 (0.2, 2.0) 0.02 –0.3 (–0.8, 0.1) 0.15
Total NA 0.03 (–0.2, 0.3) 0.73 NA NA