Objective To investigate the associated risk of epilepsy after traumatic brain injury (TBI) in a population-based retrospective cohort study.

Methods Using Taiwan's National Health Insurance Research Database of reimbursement claims, we conducted a retrospective cohort study of 19 336 TBI patients and 540 322 non-TBI participants aged ≥15 years as reference group. Data on newly developed epilepsy after TBI with 5–8 years’ follow-up during 2000 to 2008 were collected. HRs and 95% CIs for the risk of epilepsy associated with TBI were analysed with multivariate Cox proportional hazards regressions.

Results Compared with the non-TBI cohort, the adjusted HRs of developing epilepsy among TBI patients with skull fracture, severe or mild brain injury were 10.6 (95% CI 7.14 to 15.8), 5.05 (95% CI 4.40 to 5.79) and 3.02 (95% CI 2.42 to 3.77), respectively. During follow-up, men exhibited higher risks of post-TBI epilepsy. Patients who had mixed types of cerebral haemorrhage were at the highest risk of epilepsy compared with the non-TBI cohort (HR 7.83, 95% CI 4.69 to 13.0). The risk of post-TBI epilepsy was highest within the first year after TBI (HR 38.2, 95% CI 21.7 to 67.0).

Conclusions The risk of epilepsy after TBI varied by patient gender, age, latent interval and complexity of TBI. Integrated care for early identification and treatment of post-trauma epilepsy were crucial for TBI patients.