Association between poststroke epilepsy and death: A nationwide cohort study

Introduction: Poststroke epilepsy (PSE) is the most common form of acquired epilepsy after middle age. The primary aim of this study was to study the impact of PSE on prognosis. A secondary aim was to validate recent findings from smaller studies on the risk of developing PSE on a nationwide scale. Patients and methods: We performed a nationwide cohort study based on comprehensive national registries and included patients without a prior epilepsy diagnosis surviving more than 2 months after stroke, identified by the Swedish Stroke Register (Riksstroke) and linked to the National Patient Register and Cause of Death Register. Cox proportional time-updated hazard model was used to assess the risk of death, with or without multivariable adjustment for possible confounders, and multiple Cox regression was used to examine associations between PSE and clinical characteristics. Results: In 106,455 patients, PSE (defined as a seizure diagnosis more than 7 days after stroke) was detected in 7.3%, with lower cumulative incidence after ischemic stroke (6.4%) than after intracerebral haemorrhage (12.4%). Stroke severity, intracerebral haemorrhage and young age were associated with a risk of PSE. The risk of death was increased in patients with PSE (hazard ratio: 1.68, 95% confidence interval: 1.25-1.53). Also with adjustments for age, comorbidities and stroke severity, an increased risk of death associated with PSE remained. Discussion: Studies are needed on potential causes of increased mortality in PSE, such as a direct seizure-related mortality, less ambitious secondary stroke prophylaxis or rehabilitation, or impact of antiepileptic drugs on cardiovascular risk.