Post-stroke epilepsy and mortality: an observational study on healthcare administrative database

Background Post-stroke epilepsy (PSE) has been associated with hospitalization and increased mortality risk. So far, evidence on PSE and mortality risk is lacking. Therefore, this study aimed to evaluate the association between PSE and mortality in different type of stroke. Methods A retrospective observational study was conducted using healthcare administrative databases of Lombardy, a northern Italian region (16.4% of the Italian population). Patients aged 40 years or older admitted to the hospital between 1/1/2004 and 31/12/2008 with diagnosis of hemorrhagic (HS)- or ischemic (IS)- stroke were included. Diagnosis of seizure/epilepsy was identified by using discharge ICD9-CM codes, exemption code or use of antiepileptic drugs. This date was considered the index date. For each stroke cohort case of PSE was matched with 2 non post-stroke epileptic (PNS) individuals. Demographic and clinical characteristics were compared between PSE and PSN among the stroke cohorts. Cox proportional regression model was used to estimate the hazard ratio (HRs) and 95% confidence intervals (95%CI) of mortality. Results In the observed period, 13,749 of patients (4,583 PSE Vs 9,166 PSN) had IS and 4,875 (1,625 PSE Vs 3,250 PNS) had HS. Individuals were ≥75-year-old with no difference among cohorts (p value >0.9). Similarly, no differences were observed for gender (p = 1.00) and Charlson'comorbidity index (p = 1.00). Early seizure occurred in 15% of ischemic cohort and 20% of hemorrhagic one. Differences in antithrombotic drug use were observed among PSE and PSN in IS (p = 0.009) and HS cohort (p = 0.03). In ischemic cohort PSE was positively associated with increased mortality risk (HRadj: 1.67; 95%CI: 1.57-1.79), whereas no significant result was observed in hemorrhagic cohort (1.06; 0.94-1.20). Conclusions This study demonstrated a twofold increased risk of mortality in IS cohort. Further studies need to deeply characterize possible association between PSE and mortality in HS individuals. Key messages Occurrence of seizure/epilepsy in ischemic post-stroke patients represents a risk factor for morality. New studies need to clarify the contrasting result observed for hemorrhagic PSE patients.