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Table 1 General characteristics of study population

From: Blood lead concentrations and attention deficit hyperactivity disorder in Korean children: a hospital-based case control study

  Cases (n = 114) Controls (n = 114) p-value
  n (%) n (%)  
Sex, male 83 (72.8) 81 (71.1) 0.77
Economic status
 Low (< $3000) 41 (36.3) 63 (55.8) 0.01
 Middle ($3000-$4000) 35 (31.0) 30 (26.5)  
 High (> $4000) 37 (32.7) 20 (17.7)  
Paternal education
  ≥ 13 years 60 (52.6) 93 (81.6) <0.001
Maternal education
  ≥ 13 years 58 (51.3) 94 (82.5) <0.001
Paternal smoking behavior 60 (52.6) 59 (51.8) 0.50
Maternal smoking behavior 4 (3.5) 1 (0.9) 0.19
  Mean ± SD Mean ± SD  
Age (year) 8.79 ± 1.57 8.73 ± 1.65 0.77
Gestational age (week) 39.06 ± 1.89 39.12 ± 2.64 0.85
Birth weight (kg) 3.22 ± 0.59 3.30 ± 0.57 0.28
ADHD-Rating Scale
 Inattention 9.33 ± 5.74 3.81 ± 3.50 0.001
 Hyperactivity/impulsivity 6.48 ± 4.80 2.35 ± 2.67 0.001
 Total 15.82 ± 9.99 6.16 ± 5.65 0.001
Continuous Performance Test
 Omission errors 57.27 ± 18.49 47.53 ± 6.51 0.001
 Commission errors 57.36 ± 16.32 52.17 ± 13.76 0.005
 Response time 52.33 ± 12.65 51.19 ± 10.58 0.46
 Response time variability 53.68 ± 16.84 47.11 ± 8.64 0.001