Discontinuing antiepileptic drugs in patients who are seizure free on monotherapy.

OBJECTIVES: To assess the recurrence rate of epilepsy attributable to discontinuation of treatment in seizure free patients and to identify the risk factors for recurrence.
METHODS: 330 patients referred to an epilepsy centre who were seizure free for at least 2 years while on stable monotherapy were the study population. Discontinuation of antiepileptic drugs (AEDs) was proposed to all eligible patients or to their carers after discussion of the risks and benefits. Depending on whether they accepted or refused treatment withdrawal, the patients were stratified into two cohorts and followed up until seizure relapse or 31 March 1999, whichever came first. For each patient, records were taken of the main demographic and clinical variables.
RESULTS: The sample comprised 225 patients who entered the discontinuation programme and 105 who decided to continue treatment. Twenty nine patients (28%) continuing treatment had a relapse, compared with 113 (50%) of those entering the withdrawal programme. For patients continuing treatment, the probability of remission was 95% at 6 months, 91% at 12 months, 82% at 24 months, 80% at 36 months, and 68% at 60 months. The corresponding values for patients discontinuing treatment were 88%, 74%, 57%, 51%, and 48%. After adjusting for the principal prognostic factors, in patients discontinuing AEDs the risk of seizure relapse was 2.9 times that of patients continuing treatment. A relation was also found between relapse and duration of active disease, number of years of remission while on treatment, and abnormal psychiatric findings.
CONCLUSIONS: Seizure free referral patients on stable monotherapy who elect to withdraw drug treatment are at higher risk of seizure relapse compared with patients continuing treatment. Severity of disease and seizure free period are significant prognostic factors.