Table 1. Basic characteristics and response information of the study population by case status (n=1649).
| Cases N= 256 | Controls N= 1393 | |
|---|---|---|
| mean (std) | ||
| Maternal age at index birth | 32.5 (4.6) | 32.5 (4.7) |
| Paternal age at index birth | 34.6 (5.8) | 34.5 (5.5) |
| Household income level, 20011 | 7.3 (1.7) | 7.5 (1.7) |
| Index child year of birth | 1989 (5.7) | 1990 (6.1) |
| Index child birth order | 1.8 (0.9) | 2.1 (1.1) |
| Index child age at SRS | 19.1 (5.9) | 19.0 (6.2) |
| Mother age at SRS | 52.2 (4.6) | 51.5 (4.3) |
| Father age at SRS | 54.2 (5.5) | 53.6 (5.4) |
| n (%) | ||
| Race- Caucasian | 236 (92%) | 1309 (94%) |
| Maternal reported clinician-diagnosed depression2 | 86 (34%) | 271 (20%) |
| Divorced/separated as of 2001 | 22 (9%) | 84 (6%) |
| Child age category | ||
| 5-12 | 30 (12%) | 168 (12%) |
| 13-18 | 99 (39%) | 559 (40%) |
| 19+ | 127 (50%) | 666 (48%) |
| Male index child | 211 (82%) | 713 (51%) |
| Female index child | 45 (18%) | 680 (49%) |
| Index child firstborn | 116 (45%) | 447 (32%) |
| Index child ADHD (maternal report) | 116 (45%) | 135 (10%) |
| SRS forms completed | ||
| Index child form3 | 256 (100%) | 1393 (100%) |
| Mother forms | 240 (94%) | 993 (71%) |
| Father forms | 242 (95%) | 1372 (98%) |
| Complete trios | 226 (88%) | 972 (70%) |
1
Household income categories, collected on a previous NHS II biennial questionnaire, defined as: 1) <15,000, 2) 15-19,000, 3) 20-29,000, 4) 30-39,000, 5) 40-49,000, 6) 50-74,000, 7) 75-99,000, 8)100-149,000, 9)150,000. 20% did not provide income information.
2
As reported on any NHS II biennial questionnaire.
3
Child or adult version of SRS available.