Association between severity of stroke and poststroke epilepsy among patients with ischemic stroke: Mediating role of infection and early seizure.

Objective: Despite extensive studies about the direct effect of stroke severity on poststroke epilepsy (PSE), the pathway of this relationship remains unclear. We examined whether stroke-associated infection (SAI) and early seizure (ES) mediate the association between stroke severity and PSE.

Methods: Patients with ischemic stroke from two tertiary hospitals in China were included in our retrospective cohort study. PSE was identified through telephone interviews based on a validated questionnaire and supplemented by a review of medical records. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS) score, and the cohort was divided into four severity levels: mild (NIHSS score = 0-4), intermediate (NIHSS = 5-9), moderate (NIHSS = 10-14), and severe (NIHSS ≥ 15). Mediation analysis applying the Karlson-Holm-Breen method was used to explore the mediating effect of SAI and ES on the association between different stroke severity levels and PSE.

Results: A total of 2420 patients were included in the analysis, and 110 (4.5%) developed PSE during follow-up. Stroke severity was associated with SAI, ES, and PSE. Mediation analysis revealed that SAI and ES partially mediated the relationship between stroke severity and PSE. After controlling for covariates, the mediation effect proportion of SAI on the associations between moderate to severe stroke and PSE ranged from 19.71% to 29.27%. ES mediators accounted for 28.17% of the associations between a severe stroke and PSE.

Significance: SAI and ES partially mediated the association between stroke severity and PSE. This highlighted the need for additional attention to SAI and ES in patients with ischemic stroke to prevent PSE.