Table 3.

Association between blood lead concentrations and ADHD

Blood lead concentrations (range, μg/dℓ)	Crude OR (95 % CI)	p-value	Adjusted OR (95 % CI)a	p-value
Total concentration (0.18–5.35)	1.69 (1.19–2.41)	0.004	1.60 (1.04–2.45)	0.03
Quartile
1st (0.18–1.12)	Reference		Reference
2nd (1.13–1.71)	1.38 (0.65–2.90)	0.40	1.26 (0.56–2.84)	0.39
3rd (1.72–2.29)	1.20 (0.57–2.52)	0.63	1.26 (0.55–2.87)	0.61
4th (2.30–5.35)	2.96 (1.38–6.35)	0.005	2.54 (1.09–5.94)	0.03

OR odds ratio, CI confidence interval

^aAdjusted for sex, age, gestational age, birth weight, economic status, parental education, and parents’ smoking behavior