Characteristic | Cases in analysis n | Adjusted IRR (95% CI)* |
---|---|---|
All stimulants | 328 | 0.68 (0.50 to 0.91) |
Injury type | ||
Fracture† | 80 | 0.66 (0.36 to 1.20) |
Head injury‡ | 52 | 1.30 (0.63 to 2.67) |
Other type of injury | 202 | 0.59 (0.40 to 0.87) |
Day of injury | ||
Weekend injury | 44 | 0.45 (0.20 to 1.03) |
Weekday injury | 284 | 0.70 (0.51 to 0.97) |
Year of medication initiation | ||
≤2000 | 110 | 0.67 (0.41 to 1.10) |
>2000 | 218 | 0.69 (0.48 to 1.00) |
Grace period, days | ||
15 | 328 | 0.67 (0.50 to 0.90) |
45 | 328 | 0.67 (0.50 to 0.90) |
60 | 328 | 0.78 (0.50 to 0.92) |
90 | 328 | 0.71 (0.53 to 0.96) |
Exclusion of untreated time prior to medication initiation | 256 | 0.83 (0.55 to 1.20) |
Exclusion of fatal events | 327 | 0.68 (0.51 to 0.92) |
Exclusion of children who initiated treatment with dexamphetamine | 323 | 0.68 (0.51 to 0.92) |
*The IRR estimates the relative rate of injury comparing treated periods to untreated periods. All estimates are self-controlled and additionally adjusted for age in 2-year categories and season.
†Fractures include injuries coded as ‘fracture of upper limb’, ‘fracture of lower limb’ and ‘fracture of skull’.
‡Head injuries include injuries coded as ‘intracranial injuries excluding skull fracture’ and ‘fracture of skull’.
IRR, incident rate ratio.