The estimates in the literature of the risk of seizure relapse after a
ntiepileptic medications are withdrawn range from less than 10% to nea
rly 70%. There is also little coherence regarding predictors of succes
sful medication withdrawal. We performed a meta-analysis of the publis
hed literature to date to determine the risk of relapse at 1 and 2 yea
rs after discontinuation of medications and to examine the strength of
association between the risk of relapse and three commonly assessed c
linical factors: age of onset of epilepsy, presence of an underlying n
eurologic condition, and an abnormal EEG. We established criteria for
inclusion of a study in the analysis, and 25 studies met these criteri
a. Overall, the risk of relapse at 1 year was 0.25 (95% CI, 0.21 to 0.
30) and at 2 years it was 0.29 (95% CI, 0.24 to 0.34). Relative to epi
lepsy of childhood onset, epilepsy of adolescent onset was associated
with a relative risk of relapse of 1.79 (95% CI, 1.46 to 2.19). Compar
ed with childhood-onset epilepsy, adult-onset epilepsy was associated
with a relative risk of 1.34 (95% CI, 1.00 to 1.81). Patients with rem
ote symptomatic seizures were more likely to relapse than patients wit
h idiopathic seizures; the relative risk was 1.55 (95% CI, 1.21 to 1.9
8). An abnormal EEG was associated with a relative risk of 1.45 (95% C
I, 1.18 to 1.79). Although these figures help provide an estimate of a
n individual's likelihood of relapse, they should not be used as the s
ole basis on which to make the decision on discontinuation of medicati
ons. Such a decision rests heavily upon weighing the risks and benefit
s of continuing and discontinuing medications and includes considerati
on of both the risk and the consequences of relapse.