Abstracts

RATIONALE: Inadequate response to first ever antiepileptic drug (AED) is associated with poor subsequent outcome. Whether the efficacy and tolerability of first choice AEDs differ in clinical practice is not known. METHODS: We studied the response to the first prescribed AED in 470 patients (aged 9 to 93) followed up prospectively from 1984 at a single centre. Patients were considered to be seizure-free if they had no seizures for at least one year. RESULTS: Lower seizure-free rate was observed in patients with symptomatic or cryptogenic (n=351) than in those with idiopathic (n=119) epilepsy (43.5% vs. 58%, p=0.007), largely because a higher proportion of the former changed treatment due to intolerable side effects (17% vs. 8.5%, p=0.025). There was no difference in efficacy among patients receiving carbamazepine (CBZ, n=212), sodium valproate (VPA, n=101) and lamotrigine (LTG, n=78). However, those receiving CBZ (27%) had a higher incidence of adverse events leading to change of therapy than those treated with VPA (13%) or LTG (10%), and consequently had a lower seizure-free rate (CBZ vs. VPA: 41.5% vs. 57%, p=0.02; CBZ vs. LTG: 41.5% vs. 61.5%, p=0.002). There was no difference in outcome between patients treated with VPA and LTG. Nominal logistic regression analysis revealed no significant interaction in terms of outcome between the type of epilepsy and the AED chosen. CONCLUSIONS: Efficacy and tolerability need to be considered when assessing the effectiveness of AED therapy. VPA and LTG were equally effective but better tolerated than CBZ and may be more suitable as first choice for patients with newly diagnosed epilepsy. Observational studies reflecting everyday clinical practice may complement usefully evidence obtained from randomised trials.