A Cochrane review included 5 studies with a total of 440 subjects with brain tumours. The antiepileptic drugs examined were phenytoin, phenobarbital, and divalproex sodium. There was no difference between the treatment and control groups in preventing a first seizure (RR 0.94, 95% CI 0.55 to 1.61). The risk of an adverse event was higher for those on antiepileptic drugs than for participants not on antiepileptic drugs (NNH 3; RR 6.10, 95% CI 1.10 to 34.63).
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes) and by limitations in study quality (inadequate or unclear allocation concealment).