Table 1 Characteristics of school-aged boys with ADHD with and without severe internalizing/ externalizing behaviors
Variables | Internalizing behaviors (n = 1855) | Externalizing behaviors (n = 1855) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Severe (n = 818) | Not severe (n = 1037) | P value | Severe (n = 982) | Not severe (n = 873) | P value | |||||
n | (%) | n | (%) | n | (%) | n | (%) | |||
Family factors | ||||||||||
Birth order |  < 0.001 | 0.02 | ||||||||
First-born | 502 | 61.4 | 548 | 52.8 | 580 | 59.1 | 470 | 53.8 | ||
Later-born | 316 | 38.6 | 489 | 47.2 | 402 | 40.9 | 403 | 46.2 | ||
Family structure | 0.006 |  < 0.001 | ||||||||
Not with both parents | 197 | 24.1 | 188 | 18.1 | 247 | 25.1 | 144 | 16.5 | ||
With both parents | 621 | 75.9 | 849 | 81.9 | 735 | 74.9 | 729 | 83.5 | ||
Sibling status | 0.22 | 0.12 | ||||||||
Without siblings | 157 | 19.2 | 176 | 17.0 | 189 | 19.3 | 144 | 16.5 | ||
With siblings | 661 | 80.8 | 861 | 83.0 | 793 | 80.7 | 729 | 83.5 | ||
Family history of mental disorders | 0.002 | 0.001 | ||||||||
Yes | 402 | 49.1 | 435 | 41.9 | 478 | 48.7 | 359 | 41.1 | ||
No | 416 | 50.9 | 603 | 58.1 | 504 | 51.3 | 514 | 58.9 | ||
Personal factors | ||||||||||
Birth term | 0.36 | 0.08 | ||||||||
Preterm | 102 | 12.5 | 115 | 11.1 | 127 | 12.9 | 90 | 10.3 | ||
Full-term | 716 | 87.5 | 922 | 88.9 | 855 | 87.1 | 783 | 89.7 | ||
Birth mode | 0.35 | 0.20 | ||||||||
Normal spontaneous delivery | 308 | 37.7 | 369 | 35.6 | 345 | 35.1 | 332 | 38.0 | ||
Cesarean section | 510 | 62.3 | 668 | 64.4 | 637 | 64.9 | 541 | 62.0 | ||
Birth body weight (BBW) | 0.46 | 0.21 | ||||||||
 < 2500 g | 55 | 6.7 | 61 | 5.9 | 68 | 6.9 | 48 | 5.5 | ||
 ≥ 2500 g | 763 | 93.3 | 976 | 94.1 | 914 | 93.1 | 825 | 94.5 | ||
Prenatal complication |  < 0.001 | 0.03 | ||||||||
Yes | 171 | 20.9 | 132 | 12.7 | 178 | 18.1 | 125 | 14.3 | ||
No | 647 | 79.1 | 905 | 87.3 | 804 | 81.9 | 748 | 85.7 | ||
Perinatal complication |  < 0.001 | 0.06 | ||||||||
Yes | 266 | 32.5 | 248 | 23.9 | 290 | 29.5 | 224 | 25.7 | ||
No | 552 | 67.5 | 789 | 76.1 | 692 | 70.5 | 649 | 74.3 | ||
Medical comorbidity |  < 0.001 |  < 0.001 | ||||||||
Yes | 177 | 21.6 | 147 | 14.2 | 203 | 20.7 | 121 | 13.9 | ||
No | 641 | 78.4 | 890 | 85.8 | 779 | 79.3 | 752 | 86.1 | ||
Psychiatric comorbidity |  < 0.001 | 0.65 | ||||||||
Yes | 414 | 50.6 | 425 | 41.0 | 449 | 45.7 | 390 | 44.7 | ||
No | 404 | 49.4 | 612 | 59.0 | 533 | 54.3 | 483 | 55.3 | ||
Parental factors | ||||||||||
Paternal education level | 0.98 |  < 0.001 | ||||||||
 > 12 years | 338 | 41.3 | 429 | 41.4 | 355 | 36.1 | 412 | 47.2 | ||
≦12 years | 480 | 58.7 | 608 | 58.6 | 627 | 63.9 | 461 | 52.8 | ||
Maternal education level | 0.64 |  < 0.001 | ||||||||
 > 12 years | 302 | 36.9 | 372 | 35.9 | 317 | 32.3 | 357 | 40.9 | ||
≦12 years | 516 | 63.1 | 665 | 64.1 | 665 | 67.7 | 516 | 59.1 | ||
Paternal occupational status | 0.10 | 0.15 | ||||||||
Employed | 791 | 96.7 | 987 | 95.2 | 935 | 95.2 | 843 | 96.6 | ||
Unemployed | 27 | 3.3 | 50 | 4.8 | 47 | 4.8 | 30 | 3.4 | ||
Maternal occupational status | 0.83 | 0.20 | ||||||||
Employed | 530 | 64.8 | 677 | 65.3 | 652 | 66.4 | 555 | 63.6 | ||
Unemployed | 288 | 35.2 | 360 | 34.7 | 330 | 33.6 | 318 | 36.4 | ||
Paternal age at childbirth | 0.11 | 0.34 | ||||||||
 < 20 years | 8 | 1.0 | 4 | 0.4 | 8 | 0.8 | 4 | 0.5 | ||
 ≥ 20 years | 810 | 99.0 | 1033 | 99.6 | 974 | 99.2 | 869 | 99.5 | ||
Maternal age at childbirth | 0.08 | 0.002 | ||||||||
 < 20 years | 38 | 4.7 | 32 | 3.1 | 50 | 5.1 | 20 | 2.3 | ||
 ≥ 20 years | 780 | 95.3 | 1005 | 96.9 | 932 | 94.9 | 853 | 97.7 | ||