Characteristics of all children with linked EHRs in the study population
| n=3119* (weighted %)† | |
| Hyperactivity | |
| Normal | 2563 (82.8) |
| Borderline | 204 (6.5) |
| High/abnormal | 328 (10.6) |
| Conduct Problems | |
| Normal | 2404 (76.1) |
| Borderline | 391 (13.4) |
| High/abnormal | 305 (10.5) |
| Sex | |
| Boy | 1604 (51.3) |
| Girl | 1515 (48.7) |
| No of people in the household | |
| 2 | 169 (6.4) |
| 3 | 564 (18.3) |
| 4 | 1420 (43.9) |
| five or more | 966 (31.4) |
| Lone parent | |
| Lone | 586 (20.4) |
| Non-lone | 2533 (79.6) |
| Residential area | |
| Rural | 756 (26.1) |
| Urban | 2360 (73.9) |
| Household poverty | |
| OECD 60% median or above | 2213 (69.1) |
| Below OECD 60% median | 894 (30.9) |
| Maternal education | |
| Degree | 635 (19.3) |
| Diplomas in Higher Education | 344 (9.9) |
| Advanced/Advanced Subsidiary/Subsidiary levels | 401 (14.4) |
| Ordinary level/General Certificate of Secondary Education | 1248 (40.0) |
| Other | 77 (2.4) |
| None | 407 (14.0) |
| Physical activity level | |
| 3 or more days a week | 411 (14.6) |
| 2 days a week | 581 (18.5) |
| 1 day a week | 872 (27.7) |
| Less often or not at all | 1246 (39.1) |
| Country | |
| Wales | 1750 (36.3) |
| Scotland | 1369 (63.7) |
| Median (IQR) | |
| Maternal age at birth (years) | 29 (24–33) |
*Missing data: hyperactivity (24, unweighted %=0.8); CP (19, unweighted %=0.6); living area (less than 5); poverty indicator (12, unweighted %=0.4); maternal education (7, unweighted %=0.2); physical activity level (9, unweighted %=0.3); maternal age at birth (less than 5).
†Weighting was based on 1 minus the probability of non-consent, multiplied by the age 7 survey weights for data linkage and scaled to the sum of the number of consenting children.
CP, conduct problem; EHR, electronic health record; OECD, Organisation for Economic Co-operation and Development.