A topic in Clinical Evidence summarizes the results of one RCT (n=419, 28% aged < 16 years) comparing immediate treatment after a first unprovoked seizure vs no immediate treatment. There were fewer second seizures with immediate treatment at 2 years (HR 0.36, 95% CI 0.24 to 0.53) compared with no treatment, but there was no significant difference in the proportion of people achieving a 2-year remission (AR, 60% with immediate treatment vs 68% without treatment, RR 0.82, 95% CI 0.64 to 1.03).
According to a systematic review of prospective observational studies including about 2500 people, 40% of people have further seizures within 2 years of their first seizure.
Comment: The quality of evidence was downgraded by imprecise data (limited study size). The RCT lacks power to rule out the possibility that treating a first seizure alters the long term prognosis of epilepsy. The harms of antiepileptic medication must be weighed against the benefit of immediate treatment.