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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Seizure recurrence after planned discontinuation of antiepileptic drugs in seizure-free patients after epilepsy surgery: a review of current clinical experience

D Schmidt, C Baumgartner, and W Loscher.

Review published: 2004.

CRD summary

This review assessed the risk of seizure recurrence after the planned discontinuation of antiepileptic drugs (AEDs) following surgery for epilepsy. The authors concluded that one in three patients were at risk of seizure recurrence after discontinuing AEDs. The results were based on potentially biased retrospective studies, and the authors' conclusions do not adequately reflect the limitations of this evidence.

Authors' objectives

To assess the risk of seizure recurrence following the planned discontinuation of antiepileptic drugs (AEDs) after surgery for epilepsy.

Searching

MEDLINE, EMBASE and BIOSIS Previews were searched for studies published in full or as abstracts between 1980 and 2003; the search terms were stated. The reference lists of all available reports were checked. Additional information was obtained from the authors for two studies that had been reported as abstracts.

Study selection

Study designs of evaluations included in the review

Inclusion criteria for the study design were not specified. All of the included studies were retrospective studies.

Specific interventions included in the review

Studies of planned discontinuation of AEDs were eligible for inclusion. The time interval between surgery and the discontinuation of AEDs was reported in only two studies and ranged from 1 to 5 years. The comparators included partial withdrawal from AEDs and continued medication.

Participants included in the review

Studies of patients who had undergone resective surgery for epilepsy were eligible for inclusion. The age of the participants ranged from 3 months to 61 years, and most had undergone temporal lobe resections.

Outcomes assessed in the review

Studies that mentioned seizure outcome in the title or abstract were eligible for inclusion. The primary outcome assessed in the review was seizure recurrence. The review also discussed the effects of reducing AED treatment and the effect of re-instituting AED treatment after seizure recurrence.

How were decisions on the relevance of primary studies made?

The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

The paper stated that the three authors independently reviewed included studies that met the inclusion criteria. The mean percentage of patients with seizure recurrence, along with 95% confidence intervals (CIs), was extracted or calculated at the longest follow-up period for each study. For studies of adults, Kaplan-Meier estimates of seizure recurrence were calculated.

Methods of synthesis

How were the studies combined?

The overall mean percentage of patients with seizure recurrence and 95% CI were calculated. The results from two studies, one in children and another where the results were not reported separately for discontinuation and taper in adults, were not included in the calculation of the overall mean. The results were also discussed in a narrative synthesis.

How were differences between studies investigated?

Differences between the studies were discussed in the text with respect to the duration of epilepsy, age of the patients at the time of surgery, duration of seizure-free interval after surgery, and the results of magnetic resonance imaging. Study details and results were also tabulated.

Results of the review

Six retrospective studies (n=369) were included.

The mean percentage of patients with seizure recurrencefollowing discontinuation of AEDs was 33.8% (95% CI: 32.4, 35.2), based on four studies of adults after maximum follow-up from 1 to 5 years. Seizure recurrence increased with time during the follow-up period. More than 90% of adults with seizure recurrence regained control of seizures after AEDs were re-started (2 studies, n=26). However, 9% of adults developed intractable epilepsy after AED discontinuation. In the study with taper and discontinuation of AEDs, only 56% of adults regained control of seizures after AEDs were re-started.

The one study in 57 children and adolescents found the seizure recurrence rate was 16% at a mean follow-up of 67.5 months (range: 24 to 185) for all 57 children, and 20% for the sub-group of 41 children with temporal lobe epilepsy. Seven of the 11 children with seizure recurrence were seizure-free after re-starting AEDs.

Authors' conclusions

The risk of seizure recurrence after discontinuing AEDs is one in three for patients who are seizure-free following epilepsy surgery.

CRD commentary

The review question was clear in terms of the intervention, participants and outcomes. Inclusion criteria were not defined for the study design. Three relevant databases were searched but there were no attempts to locate unpublished studies, thus raising the possibility of publication bias. It was unclear whether any language limitations were applied. The methods used to select studies were not described, so it is not known whether any efforts were made to reduce errors and bias. The authors do not appear to have undertaken any validity assessment.

The data were pooled but heterogeneity among the studies was not assessed, although an examination of the tables shows similar outcomes across studies. There was a discrepancy between the table and text regarding the CIs reported for the pooled result of the primary outcome. The authors discussed the association between seizure recurrence and some variables. The results were based on a small number of retrospective studies with low participant numbers, which have, as the authors acknowledged, potential for selection bias. However, the authors' conclusions do not adequately reflect the poor quality of the evidence on which the results were based.

Implications of the review for practice and research

Practice: The authors stated that the small risk of uncontrolled epilepsy after the discontinuation or reduction of AEDs must be discussed with patients.

Research: The authors stated that there is a need for a randomised, double-blind, placebo-controlled trial to compare partial and complete discontinuation of AEDs with continued single AED treatment in patients who have been seizure-free for 2 years after surgery.

Bibliographic details

Schmidt D, Baumgartner C, Loscher W. Seizure recurrence after planned discontinuation of antiepileptic drugs in seizure-free patients after epilepsy surgery: a review of current clinical experience. Epilepsia 2004; 45(2): 179-186. [PubMed: 14738426]

Indexing Status

Subject indexing assigned by NLM

MeSH

Anticonvulsants /therapeutic use; Epilepsy /drug therapy /surgery; Humans; Recurrence

AccessionNumber

12004009287

Database entry date

31/03/2006

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 14738426

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