Risk of seizure relapse after antiepileptic drug withdrawal in adult patients with focal epilepsy

- The high-risk period of seizure relapse is the first 2 years after withdrawal.
- Beyond 5 years after withdrawal, seizures rarely relapse (relapse rate < 1%).
- A seizure-free period for less than 4 years before withdrawal is a risk factor for seizure relapse following AED withdrawal.
- A longer duration of active epilepsy is a risk factor for seizure relapse following AED withdrawal.

ObjectiveThe objective of this study was to estimate the risk of a seizure relapse and the high-risk period of recurrence after antiepileptic drug (AED) withdrawal and to determine the predictive factors for a seizure relapse in adult patients with focal epilepsy who were seizure-free for more than 2 years.MethodsUsing the Wenzhou Epilepsy Follow-Up Registry Database, 200 adult patients with focal epilepsy were recruited, who were undergoing follow-up, met the inclusion criteria of this study, were seizure-free for more than 2 years, began withdrawing between June 2003 and June 2014, and were followed up prospectively for at least 1 year or until a seizure relapse. The risk of recurrence and the time to seizure relapse were analyzed by the Kaplan-Meier method, and the predictive factors were identified by the Cox proportional hazard regression model.ResultA total of 99 patients had an unprovoked relapse during the follow-up period. The relapse rate was 49.5%, and each year, the recurrence probability of 12, 24, 36, 48, 60, 72, and 84 months after AED withdrawal was 24.0%, 20.4%, 8.3%, 2.7%, 4.6%, 0.97%, and 0.98%, respectively. The two independent risk factors for recurrence after withdrawal in adult patients with focal epilepsy were a longer duration of active epilepsy and a shorter seizure-free period before withdrawal.ConclusionThe high-risk period of a seizure relapse in adult patients with focal epilepsy is the first 2 years after withdrawal, and beyond 5 years after withdrawal, seizures rarely relapse (relapse rate < 1%). A seizure-free period for less than 4 years before withdrawal is a predictive factor of risk for seizure recurrence after AED withdrawal in adult patients with focal epilepsy.