Annegers et al., 1980

Retrospective cohort

2,747 patients of Olmsted County, MN, with head injuries sustained 1935–1974 compared with age-, sex-specific rates in general population; followed for 28,176 person-years Excluded deaths within 1 mo, seizures before TBI, prior epilepsy, second head injury, prior TBI, seizure within 1 week of TBI, febrile seizures 1,132 of 2,747 patients (41%) were children less than 15 years old

TBI determined by health-care provider, documented in medical record 195 severe head injuries: documented brain contusion (diagnosed by observation during surgery, or from focal neurologic abnormalities), intracranial hematoma, or at least 24 h of unconsciousness or PTA

Seizures determined from medical records

SIR; seizures in adults, children: < 1 year after trauma, SIR, 12.7 (95% CI, 7.7–20); 1–4 years after trauma, SIR, 4.4 (95% CI, 2.7–6.9); 5+ years after trauma, RR, 1.4 (95% CI, 0.7–2.5); overall SIR, 3.6 (95% CI, 2.7–4.8)

Age- and sex-matched controls

Children included in risk estimate; results include children, whose rates of seizures may be different from adults’ rates

912 moderate head injuries: skull fractures or head injuries, causing at least 0.5 h of unconsciousness or PTA 1,640 mild head injuries: no fracture but unconsciousness or PTA for less than 30 min