Out-of-hospital versus in-hospital status epilepticus: the role of etiology and comorbidities

Background: To identify differences in clinical characteristics between patients with out-of-hospital and in-hospital status epilepticus (SE) onset, and to evaluate the influence of SE onset setting on 30-day mortality and SE cessation. Methods: We included consecutive patients with SE admitted from 2013 to 2021 at Modena Academic Hospital. A propensity score was performed with clinical variables unevenly distributed between the two groups. Results: 711 patients were included; 55.8% (397/711) with an out-of-hospital and 44.2% (314/711) with an in-hospital onset. Patients with in-hospital SE onset were older, had a higher frequency of comorbidities, acute and/or potentially fatal etiologies, impaired consciousness before treatment, and nonconvulsive or myoclonic SE. No difference was found in SE cessation between the groups. Patients with in-hospital SE had higher 30-day mortality (127/314, 62.9% versus 75/397, 37.1; p <0.001). In-hospital onset was an independent risk factor for 30-day mortality (adjusted OR of 1.720; 95% CI: 1.107-2.674; p = 0.016). In the propensity group (n = 244), no difference was found in 30-day mortality and SE cessation between out-of-hospital and in-hospital SE onset groups (36/122, 29.5% versus 34/122, 27.9%; p=0.888; and 47/122, 38.5% versus 39/122; 32%; p = 0.347, respectively). Conclusion: In-hospital SE is associated with higher 30-day mortality without difference in SE cessation. The two groups differ considerably for age, acute and possibly fatal etiologies, comorbidities, and SE semiology. The patient location at SE onset is an important prognostic predictor. However, the increased mortality is probably unrelated to the setting of SE onset and reflects intrinsic prognostic predictors.