Association of Posttraumatic Epilepsy With Long-term Functional Outcomes in Individuals With Severe Traumatic Brain Injury

Background and Objective Nearly one-third of patients with severe traumatic brain injury (TBI) develop posttraumatic epilepsy (PTE). The relationship between PTE and long-term outcomes is unknown. We tested whether, after controlling for injury severity and age, PTE is associated with worse functional outcomes after severe TBI. Methods We performed a retrospective analysis of a prospective database of patients with severe TBI treated from 2002 through 2018 at a single level 1 trauma center. Glasgow Outcome Scale (GOS) was collected at 3, 6, 12, and 24 months postinjury. We used repeated-measures logistic regression predicting GOS, dichotomized as favorable (GOS 4–5) and unfavorable (GOS 1–3), and a separate logistic model predicting mortality at 2 years. We used predictors as defined by the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) base model (i.e., age, pupil reactivity, and GCS motor score), PTE status, and time. Results Of 392 patients who survived to discharge, 98 (25%) developed PTE. The proportion of patients with favorable outcomes at 3 months did not differ between those with and without PTE (23% [95% Confidence Interval [CI]: 15%–34%] vs 32% [95% CI: 27%–39%]; p = 0.11) but was significantly lower at 6 (33% [95% CI: 23%–44%] vs 46%; [95% CI: 39%–52%] p = 0.03), 12 (41% [95% CI: 30%–52%] vs 54% [95% CI: 47%–61%]; p = 0.03), and 24 months (40% [95% CI: 47%–61%] vs 55% [95% CI: 47%–63%]; p = 0.04). This was driven by higher rates of GOS 2 (vegetative) and 3 (severe disability) outcomes in the PTE group. By 2 years, the incidence of GOS 2 or 3 was double in the PTE group (46% [95% CI: 34%–59%]) compared with that in the non-PTE group (21% [95% CI: 16%–28%]; p < 0.001), while mortality was similar (14% [95% CI: 7%–25%] vs 23% [95% CI: 17%–30%]; p = 0.28). In multivariate analysis, patients with PTE had lower odds of favorable outcome (odds radio [OR] 0.1; 95% CI: 0.1–0.4; p < 0.001), but not mortality (OR 0.9; 95% CI: 0.1–1.9; p = 0.46). Discussion Posttraumatic epilepsy is associated with impaired recovery from severe TBI and poor functional outcomes. Early screening and treatment of PTE may improve patient outcomes.