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

Abstract

Background: Epilepsy is a chronic neurological disorder which affects millions of people around the world. Antiepileptic drugs (AED) are the main interventions used to prevent seizures and control epilepsy. Although effective in most cases, AEDs are related to long-term adverse effects, such as cognitive and behavioural alterations. Thus when epilepsy is in remission, it may be in the individual's best interest to discontinue medication. However, the optimal timing of AED discontinuation is still unknown.This is an updated version of the original Cochrane review published in Issue 3, 2001.

Objectives: (1) To quantify and compare risk of seizure recurrence, status epilepticus and mortality after early and late AED discontinuation in adult and pediatric epilepsy patients.(2) To assess which variables modify the risk of seizure recurrence.(3) To define a subpopulation in which early AED discontinuation is safe.

Search methods: We searched the Cochrane Epilepsy Group Specialised Register (June 2014); CENTRAL (Issue 5, The Cochrane Library, May 2014); MEDLINE (1946 to June 2014); CINAHL (23 June 2014); Scopus (1823 to June 2014); ClinicalTrials.gov (23 June 2014); and WHO International Clinical Trials Registry Platform (23 June 2014). We also checked the reference lists of studies found through the electronic searches.

Selection criteria: Randomised controlled trials that evaluate withdrawal of AEDs after varying periods of seizure remission in adults and children with epilepsy. Included studies compared an early AED discontinuation time (defined as a period of remission of seizures of less than two years) versus a late AED discontinuation time (defined as a period of remission of seizures of more than two years).

Data collection and analysis: Two authors independently extracted data and assessed trial quality. Risk ratio (RR) with 95% confidence interval (CI) was calculated for each trial. Summary RRs and 95% CIs for dichotomous data were calculated using a fixed-effect model. A test of statistical heterogeneity was conducted for each pooled risk ratio calculation. Each included study underwent a 'Risk of bias' assessment, based on the Cochrane Handbook recommendations, and we examined the overall quality of information through the GRADE system, presented in two 'Summary of Findings' tables.

Main results: Five trials were included in this review, representing 924 randomised children with epilepsy, all under 16 years of age at randomisation, with a median follow-up of 5.6 years. No eligible trial evaluated adults or assessed mortality or status epilepticus as outcomes. The pooled risk ratio for seizure relapse after AED withdrawal was 1.34 (95% CI 1.13 to 1.59, P = 0.0007). Conforming to 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 8 (95% CI 5 to 20). Early discontinuation was associated with greater relapse rates in people with partial seizures with a pooled risk ratio of 1.51 (95% CI 0.97 to 2.35, P = 0.07). Absence type epilepsy showed a lower risk of relapse. Variables associated with higher risk of seizure relapse were abnormal EEG findings (pooled RR 1.44, 95% CI 1.13 to 1.83, P = 0.003), especially epileptiform activity (RR 2.58, 95% CI 2.03 to 3.28, P < 0.0001); epilepsy onset before 2 years or after 10 years of age; history of status epilepticus; intellectual disability (IQ < 70); and high seizure frequency before and during treatment. Gender and family history did not show any significant influence over seizure relapse. Overall, the included trials were classified as low or unclear risk of bias where methodological information was not reported and could not be provided by original study authors.

Authors' conclusions: There is evidence to support waiting for at least two seizure-free years before discontinuing AEDs in children, particularly if individuals have an abnormal EEG or partial seizures, or both. There is insufficient evidence to establish when to withdraw AEDs in children with generalised seizures. There is no evidence to guide the timing of withdrawal of AEDs in seizure-free adults. Further high-quality randomised controlled trials are needed, particularly recruiting adults and recruiting those with generalised seizure types, to identify the optimal timing of AED withdrawal and risk factors predictive of relapse.

1

1 Study flow diagram.

2

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

3

Forest plot of comparison: 1 Early versus late withdrawal, outcome: 1.1 Seizure relapse rate by time of withdrawal.

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Forest plot of comparison: 1 Early versus late withdrawal, outcome: 1.2 Seizure relapse rate in people with partial epilepsy by time of withdrawal.

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Forest plot of comparison: 2 Abnormal versus normal EEG, outcome: 2.1 Seizure relapse rate by EEG findings.

1.1. Analysis

Comparison 1 Early versus late withdrawal, Outcome 1 Seizure relapse rate by time of withdrawal.

1.2. Analysis

Comparison 1 Early versus late withdrawal, Outcome 2 Seizure relapse rate in people with partial epilepsy by time of withdrawal.

2.1. Analysis

Comparison 2 Abnormal versus normal EEG, Outcome 1 Seizure relapse rate by EEG findings.