Early versus late antiepileptic drug withdrawal for people with epilepsy in remission.

BACKGROUND: Antiepileptic drugs ( AEDs) are used to prevent seizures but are associated with both short and long term adverse effects. When epilepsy is in remission, it may be in the patient's best interest to discontinue medication. However, the optimal timing of AED discontinuation is not known. OBJECTIVES: To quantify seizure relapse risk after early (less than two seizure free years) versus late (more than two seizure free years) AED withdrawal in adult and pediatric epilepsy patients. To assess which variables modify the risk of seizure recurrence. SEARCH STRATEGY: We searched the Cochrane Epilepsy Group trials register, the Cochrane Controlled trials register (Cochrane Library Issue 4, 2000), MEDLINE (January 1996 to January 2001), EMBASE, Index Medicus, CINAHL, as well as hand-searching of journals. SELECTION CRITERIA: Randomized controlled trials that evaluate withdrawal of AEDs after varying periods of seizure remission in adult and pediatric epilepsy patients with or without blinding were included. Included studies compared an early versus late AED discontinuation. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed trial quality. Relative risks with 95% confidence intervals were calculated for each trial. Summary relative risks and 95% confidence intervals for dichotomous data were calculated using a random effects model. A test of statistical heterogeneity was conducted for each pooled relative risk calculation. MAIN RESULTS: Seven eligible controlled trials were included in the analysis representing 924 randomized pediatric patients. There were no eligible trials evaluating adult seizure free patients. The pooled relative risk for seizure relapse in early versus late AED withdrawal was 1.32 (95% confidence interval 1.02 to 1.70). On the basis of this estimate, the number needed to harm, that is expose an individual to a higher risk of seizure relapse because of early withdrawal of AED, is 10. Early discontinuation was associated with greater relapse rates in patients with partial seizures[pooled RR = 1.52; 95% confidence interval 0.95 to 2.41] or an abnormal EEG [pooled RR=1.67; 95% confidence interval 0.93 to 3.00]. REVIEWER'S CONCLUSIONS: There is evidence to support waiting for at least two or more seizure free years before discontinuing AEDs in children, particularly if individuals have an abnormal EEG and partial seizures. There is insufficient evidence to establish when to withdraw AEDs in pediatric patients with generalized seizures. There is no evidence to guide the timing of withdrawal of AEDs in adult seizure free patients. Further blinded randomized controlled trials are needed to identify the optimal timing of AED withdrawal and risk factors predictive of relapse.