Three-Year Mortality After First Acute Symptomatic Seizure: A Prospective, Population-Based Study in Ireland

Acute symptomatic seizures (ASyS) are clinical seizures occurring at the time of a systemic insult or in close temporal association with a documented brain injury. We aimed to determine the 3-year mortality following a first ASyS.

We previously conducted a prospective, population-based cohort comprising all individuals with a first seizure during 2017 from a defined geographic area. Individuals with ASyS were identified from this cohort using ILAE criteria and stratified by provoking factor. Mortality was assessed at 30 days, 1 year, and 3 years following the event, and age-standardized mortality ratios (SMRs) were calculated at 1 and 3 years using age-matched and sex-matched national mortality data.

Among 207 cases of first ASyS, identified from a population of 542,868, there were 61 deaths (29.5%) during 3 years of follow-up. Mortality at 30 days, 1 year, and 3 years was 12.6%, 22.2%, and 29.5%, respectively. The SMR was 19.7 (95% CI 14.4-26.3) at 1 year and 10.4 (95% CI 7.9-13.4) at 3 years. Mean age at first ASyS was 52.1 years and at death 70.5 years. Excluding the substance use group, 3-year mortality rose to 45.5% (50/110). Pneumonia was the most frequent cause of death (17/61, 27.9%).

ASyS is a common presentation and is associated with markedly increased mortality over 3 years. These findings underscore the prognostic importance of ASyS as a clinical indicator of increased long-term mortality, particularly in medically complex patients.