Table 1. Descriptive statistics.
| ADHD | Controls | P-valuea | |||||
| Individuals | 28,914 (2.4) | 1,167,830 (97.6) | <0.001 | ||||
| Female | 11,839 (40.9) | 570,840 (48.9) | <0.001 | ||||
| Immigrant | 1,824 (6.3) | 94,966 (8.1) | <0.001 | ||||
| At least 1 missing observation of EA | 1,422 (4.9) | 65,509 (5.6) | <0.001 | ||||
| Deceased | 291 (1.0) | 1,814 (0.2) | <0.001 | ||||
| Diagnosis of developmental disorder | 5,379 (18.6) | 8,705 (0.7) | <0.001 | ||||
| Diagnosis of intellectual disability | 715 (2.5) | 1,570 (0.1) | <0.001 | ||||
| Lifetime educational attainment and prevalence of ADHD by year of compulsory school graduation (%) | |||||||
| Graduation year | ADHD | Compulsory | Secondary | Tertiary | Compulsory | Secondary | Tertiary |
| 1998 | 1.7 | 37.3 | 48.8 | 13.9 | 8.5 | 47.0 | 44.5 |
| 1999 | 1.8 | 35.6 | 52.3 | 12.1 | 7.9 | 49.5 | 42.7 |
| 2000 | 1.8 | 35.0 | 52.8 | 12.1 | 7.7 | 50.5 | 41.8 |
| 2001 | 1.9 | 35.4 | 53.2 | 11.4 | 7.5 | 53.0 | 39.5 |
| 2002 | 1.9 | 35.4 | 54.7 | 9.9 | 7.3 | 55.3 | 37.4 |
| 2003 | 2.2 | 35.9 | 57.1 | 7.0 | 7.4 | 57.9 | 34.7 |
| 2004 | 2.3 | 39.3 | 54.8 | 5.9 | 7.7 | 61.5 | 30.9 |
| 2005 | 2.7 | 39.4 | 56.5 | 4.1 | 8.2 | 65.4 | 26.4 |
| 2006 | 2.9 | 39.8 | 56.7 | 3.4 | 8.6 | 71.4 | 20.0 |
| 2007 | 3.1 | 40.8 | 57.8 | 1.4 | 8.9 | 79.1 | 12.1 |
| 2008 | 3.6 | 42.3 | 57.3 | 0.4 | 9.1 | 87.4 | 3.5 |
N (%) unless specified.
a P-value calculated based on Pearson’s chi-squared test of counts in each variable (e.g., female sex) over ADHD status.