Abstracts

Rationale: Early posttraumatic seizures (EPS) occur following traumatic brain injury (TBI) and have been reported to be associated with poorer outcomes and development of posttraumatic epilepsy (PTE). We evaluated risk factors for EPS, associated morbidity, contribution to PTE, and mortality.

Methods: We conducted an Australian registry-based cohort study of adults (aged ≥18 years) with moderate to severe TBI from January 2005 to December 2019. Using ICD-10-AM codes, patients with EPS were identified whilst patients with pre-existing epilepsy were excluded. Evaluation of clinical data included demographic and pre-existing illnesses, causes of injury and injury specifics, in-hospital metrics, 2-year outcomes including PTE, and post-discharge mortality. Multivariable analysis was used to identify important risk factors for, and outcomes of, EPS. Patient-reported outcomes were matched by adjusting for significant risk factors identified on multivariable analysis. Adaptive least absolute shrinkage and selection operator (LASSO) regression was used to build a prediction model for EPS in 80% of the patients and validated in the rest 20%.

Results: 15,152 adults with moderate-severe TBI were included and, of these, 416 were identified as having experienced EPS (2.7%). A small number (n=27, 0.2%) of patients had status epilepticus. Significant risk factors for developing EPS were younger age, higher Charlson Comorbidity Index, TBI sustained from a low fall, subdural hemorrhage (SDH), subarachnoid hemorrhage (SAH), Injury Severity Scale (ISS), and greater head injury severity, measured using the Abbreviated Injury Scale (AIS) and Glasgow Coma Score (GCS) (Table 1). Adjusted outcomes of EPS showed an association with increased ICU admission and length of stay, ventilation and duration, hospital length of stay, discharge to inpatient rehabilitation rather than home, but not in-hospital mortality. Follow up patient-matched outcomes of EPS showed worse overall outcomes at 24 months including mortality (RR=2.14, 95% confidence interval [CI]: 1.32-3.46, P=0.002), development of PTE (RR=2.91, 95% CI: 2.22-3.81, P< 0.001), and use of antiseizure medications (RR=2.44, 95% CI: 1.98-3.02, P< 0.001). Risk of long-term mortality via linkage with the death registry was increased for patients with EPS (RR=1.25, 95% CI: 1.03-.51, P=0.02). Adaptive LASSO regression prediction model for EPS (Table 2) demonstrated an overall performance of area under the receiver operating characteristics curve of 0.72 (95% CI: 0.66-0.79) in the validation set with a maximum value of Youden's index of 0.39 at total penalized coefficient value of 1.05 (sensitivity=66% and specificity=73%).