TABLE 1.
Baseline and Follow-up Characteristics of Non-ADHD Controls and ADHD Cases; ADHD Cases Separately by Treatment Status
| Characteristic | ADHD Case Status | Pa | ADHD Cases Treated With Stimulants for ≥3 Monthsb | Pa | ||
|---|---|---|---|---|---|---|
| Non-ADHD Controls (N = 394) | ADHD Cases (N = 243) | Yes (N = 171) | No (N = 65) | |||
| Baseline | ||||||
| Gender, n (%) | .88 | .027 | ||||
| Male | 286 (72.6) | 175 (72.0) | 130 (76.0) | 40 (61.5) | ||
| Female | 108 (27.4) | 68 (28.0) | 41 (24.0) | 25 (38.5) | ||
| Birth length (cm), mean (SD) | 51.8 (2.8) | 51.7 (2.9) | .73 | 51.7 (3.0) | 51.8 (2.7) | .83 |
| Birth wt (g), mean (SD) | 3522 (560) | 3456 (566) | .15 | 3449 (547) | 3472 (619) | .78 |
| Maternal age at subject’s birth, mean (SD) | 26.4 (4.7) | 26.1 (4.9) | .47 | 26.2 (4.7) | 26.1 (5.4) | .87 |
| Maternal education at subject’s birth, n (%) | .011 | .29 | ||||
| Not available, n | 42 | 19 | 15 | 4 | ||
| Less than high school | 26 (7.4) | 14 (6.3) | 9 (5.8) | 5 (8.2) | ||
| High school graduate | 106 (30.1) | 97 (43.3) | 72 (46.2) | 21 (34.4) | ||
| Some college | 130 (36.9) | 71 (31.7) | 48 (30.8) | 21 (34.4) | ||
| College graduate | 90 (25.6) | 42 (18.8) | 27 (17.3) | 14 (23.0) | ||
| Follow-up | ||||||
| Age at last recorded height measurement (y), mean (SD) | 24.6 (5.8) | 26.8 (5.0) | <.001 | 26.8 (4.8) | 26.7 (5.7) | .91 |
| Number of height measurements per subject in 3-y age windows, median (IQR) | ||||||
| Birth to <3 y | 9 (7, 12) | 8 (6, 12) | 8 (6, 12) | 8 (6, 9) | ||
| 3 to <6 y | 3 (2, 6) | 4 (2, 7) | 4 (2, 7) | 3 (2, 4) | ||
| 6 to <9 y | 3 (2, 6) | 4 (2, 7) | 5 (3, 8) | 4 (2, 6) | ||
| 9 to <12 y | 4 (2, 6) | 5 (3, 8) | 5 (3,8) | 5 (4, 7) | ||
| 12 to <15 y | 4 (2, 6) | 5 (3, 8) | 5 (3, 8) | 4 (3, 7) | ||
| 15 to <18 y | 3 (1, 5) | 3 (2, 6) | 4 (2, 7) | 3 (1, 5) | ||
| ≥18 y | 5 (1, 12) | 8 (3, 18) | 8 (3, 18) | 9 (2, 18) | ||
| Overall | 35 (26, 49) | 44 (33, 60) | <.001 | 46 (34, 62) | 41 (33, 53) | .16 |
| Age met ADHD research criteria (y), mean (SD) | n/a | 10.3 (3.6) | n/a | 9.9 (3.4) | 11.3 (3.8) | .006 |
IQR, interquartile range.
a
Comparisons between groups were evaluated by using the χ2 test for gender, the 2-sample t test for birth length, birth wt, and age, and the Wilcoxon rank-sum test for the maternal education categories and number of height measurements.
b
Duration of stimulant treatment was unknown for 7 of the 243 ADHD cases.