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.