Trajectories of long-term survival after status epilepticus.

Objectives: To investigate the trajectories of clinical characteristics and prognostic factors among long-term survivors of status epilepticus (SE), given the high mortality during acute hospitalization and in subsequent years.

Methods: Adult patients (≥18 years of age) with first-time, non-anoxic SE were identified and included from University Hospitals in Oslo (Norway), Odense (Denmark), Frankfurt, and Marburg (Germany). Demographics, etiology, comorbidities, and seizure characteristics were assessed. Poisson regression was used to model mortality rates over the follow-up period.

Results: Between 2001 and 2017, we included 1306 patients (median follow-up: 17.4 months). The estimated cumulative proportion surviving at 3, 12, 24, and 36 months were 94.0%, 73.0%, 51.1%, and 39.5%, respectively, with a similar increase in mortality after discharge across all cohorts. Daily mortality peaked during the first 150 days; mortality trajectories differed depending on etiology, SE duration, and age. The clinical characteristics of survivors changed during long-term follow-up; long-term survivors (>36 months) were younger, had shorter SE durations, and had different underlying etiologies. The relative impact of different prognostic factors on the daily mortality shifted during long-term follow-up. Although most established prognostic factors strongly influenced in-hospital mortality, the relative impact of SE duration, comorbidities, and remote symptomatic etiologies first peaked after 6 months.

Significance: The optimal time point to assess survival in the acute phase is at 6 months, whereas evaluating survival after 2.5 years provides reliable estimates of long-term mortality. Assessing SE survival at discharge underestimates the impact of remote symptomatic etiologies and duration of SE on long-term survival.