If a first antiepileptic drug fails to control a child's epilepsy, what are the chances of success with the next drug?

Objective: This study was carried out to determine how often a child's epilepsy is controlled and remits if a first antiepileptic drug (AED) fails to control seizures. Study design: We used the Nova Scotia population-based epilepsy study, which identified children between 1977 and 1985 who had two or more unprovoked seizures without progressive cause and followed them up for at least 4 years. Seizure types were partial, primary, and secondarily generalized (excluding absence seizures). The study documented success or failure of the initial AED in the first year of treatment, as well as long-term seizure control and remission. Results: The number of eligible children was 417, with an average follow-up period of 8 years. The initial prescribed AEDs were phenobarbital (48%), carbamazepine (38%), and phenytoin (11%). Overall, 345 (83%) children received only one AED in the first year of treatment; 61% became free of seizures and no longer required AED treatment at the end of follow-up (remission). Only 4% of those treated with a single AED during the first year later experienced intractable epilepsy. In contrast, 72 of 417 (17%) had inadequate seizure control with their first AED and received a second AED, with only 42% having complete remission of their epilepsy. The 72 children in whom seizures were not controlled with the first AED were more likely to have neurologic deficits (p = 0.01) and complex partial seizures (p = 0.01), and 29% had intractable epilepsy (p < 0.0001). Conclusions: If the first AED is not efficacious, the outcome is less favorable, although many children will have remission of their epilepsy. Invasive or complex treatments for epilepsy with partial and generalized tonic-clonic seizures should not be used until at least two AEDs have failed to control seizures.