Risk of recurrence after a first unprovoked seizure with different risk factors: A 10-year prospective cohort study.

Objective: To evaluate the recurrence risk following a first unprovoked seizure using both single-factor and multiple-factor approaches, as well as to further analyze the potential risk factors associated with recurrence.

Methods: In a prospective cohort study, a total of 201 individuals who experienced their initial unprovoked seizure were recruited from January 2010 to December 2019. The cumulative recurrence rates were calculated by Kaplan-Meier survival curves. Multivariate analyses for recurrence risk were conducted utilizing the Cox regression model. Additionally, interaction effects were evaluated by quantifying the attributable proportion due to interaction (AP).

Results: The cumulative recurrence rates were as follows: 29.4 % at 6 months, 35.8 % at 1 year, 41.1 % at 2 years, 47.9 % at 5 years, and 57.5 % at 10 years. Notably, the majority of recurrences, specifically 61.2 %, manifested within the initial 6 months following the onset, with 74.4 % occurring within the first year, and 82.6 % within the initial 2 years. The recurrence risk of patients with epileptic abnormal discharges on VEEG, nocturnal seizure, abnormal MRI, prior brain insult and focal seizure was 71.9 %, 61.4 %, 61.5 %, 75.0 %, and 69.7 %, respectively. Epileptiform discharges (RR 2.5, 95 % CI 1.4-4.3, P=0.001) and prior brain insult (RR 2.1, 95 % CI 1.2-3.7, P=0.007) were predictors of recurrence. Interaction analysis showed the combination of epileptiform discharges and prior brain insult was associated with a 7-fold increased risk of recurrence (RR 7.0, 95 %CI 3.5-14.2)，with AP estimated at 0.34, the combination of epileptiform discharges and nocturnal seizure was associated with a 4-fold increased risk of recurrence(RR 4.3, 95 %CI 2.4-7.4), with AP estimated at -0.25,and the combination of prior brain insult and nocturnal seizures was associated with a 4-fold increased risk of recurrence(RR 4.1, 95 %CI 1.9-8.9), with AP estimated at -0.03.

Conclusions: Patients with epileptiform discharges VEEG, nocturnal seizures, abnormal MRI findings, prior brain insult, or focal seizures exhibited a substantial recurrence rate. Specifically, the presence of epileptiform discharges in VEEG recordings, and a history of prior brain insult were identified as independent risk factors associated with recurrence following an initial unprovoked seizure. Notably, individuals with multiple risk factors exhibited a significantly higher recurrence risk compared to those with no or a single risk factor.