Risk of ADHD Medication Use Among Boys Born 2005–2007 by Birth Month
| . | 2005 . | 2006 . | 2007 . | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | |
| Total | 30 580 | 1967 (6.4) | — | 31 414 | 1941 (6.2) | — | 31 380 | 1867 (5.9) | — |
| Follow-up on December 31, 2017 | |||||||||
| January to April (ref) | 9911 | 529 (5.3) | 1 | 10 500 | 572 (5.4) | 1 | 10 350 | 548 (5.3) | 1 |
| May to August | 10 638 | 705 (6.6) | 1.24*** (1.10–1.40) | 10 822 | 665 (6.1) | 1.13* (1.01–1.27) | 10 927 | 652 (6.0) | 1.13* (1.01–1.27) |
| September to December | 10 031 | 733 (7.3) | 1.39*** (1.24–1.54) | 10 092 | 704 (7.0) | 1.29*** (1.16–1.45) | 10 103 | 666 (6.6) | 1.26***(1.12–1.41) |
| Follow-up at the end of the year of eighth birthday | |||||||||
| January to April (ref) | 9911 | 225 (2.3) | 1 | 10 500 | 306 (2.9) | 1 | 10 350 | 322 (3.1) | 1 |
| May to August | 10 638 | 350 (3.3) | 1.27** (1.07–1.50) | 10 822 | 362 (3.3) | 1.15 (0.99–1.34) | 10 927 | 422 (3.9) | 1.25** (1.08–1.44) |
| September to December | 10 031 | 407 (4.4) | 1.67*** (1.42–1.97) | 10 092 | 423 (4.2) | 1.45*** (1.25–1.68) | 10 103 | 472 (4.7) | 1.51*** (1.31–1.74) |
| . | 2005 . | 2006 . | 2007 . | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | Persons . | Cases With ADHD Medication, n (%) . | HR (95% CI) . | |
| Total | 30 580 | 1967 (6.4) | — | 31 414 | 1941 (6.2) | — | 31 380 | 1867 (5.9) | — |
| Follow-up on December 31, 2017 | |||||||||
| January to April (ref) | 9911 | 529 (5.3) | 1 | 10 500 | 572 (5.4) | 1 | 10 350 | 548 (5.3) | 1 |
| May to August | 10 638 | 705 (6.6) | 1.24*** (1.10–1.40) | 10 822 | 665 (6.1) | 1.13* (1.01–1.27) | 10 927 | 652 (6.0) | 1.13* (1.01–1.27) |
| September to December | 10 031 | 733 (7.3) | 1.39*** (1.24–1.54) | 10 092 | 704 (7.0) | 1.29*** (1.16–1.45) | 10 103 | 666 (6.6) | 1.26***(1.12–1.41) |
| Follow-up at the end of the year of eighth birthday | |||||||||
| January to April (ref) | 9911 | 225 (2.3) | 1 | 10 500 | 306 (2.9) | 1 | 10 350 | 322 (3.1) | 1 |
| May to August | 10 638 | 350 (3.3) | 1.27** (1.07–1.50) | 10 822 | 362 (3.3) | 1.15 (0.99–1.34) | 10 927 | 422 (3.9) | 1.25** (1.08–1.44) |
| September to December | 10 031 | 407 (4.4) | 1.67*** (1.42–1.97) | 10 092 | 423 (4.2) | 1.45*** (1.25–1.68) | 10 103 | 472 (4.7) | 1.51*** (1.31–1.74) |
Cox proportional hazards regression model. Cases include all the children who had ≥1 reimbursed purchase of ADHD medication by the end of follow-up (% = cumulative incidence). CI, confidence interval; ref, reference category; —, not applicable.
P ≤ .001
P ≤ .01
P ≤ .05.