Abstract

BACKGROUND AND OBJECTIVES: Seizure freedom is the optimal response to antiepileptic treatment. In previous studies, it has been shown that between 61% and 71% of children with epilepsy achieve seizure freedom, whereas 7% to 20% have drug-resistant epilepsy. The definition of drug resistance has not been consistent across studies, and there is a lack of contemporary population-based data. We used data from a large nationwide child cohort to provide such information, implementing the current standard definition of drug resistance.

METHODS: The study was based on the Norwegian Mother and Child Cohort Study. Potential epilepsy cases were identified through registry linkages and parental questionnaires. Medical record reviews and parental interviews were used to collect clinical information and to classify seizures, epilepsies, and etiologies.

RESULTS: The cohort included 112745 eligible children aged 3 to 13 years (median age 7 years) at end of follow-up. Of these, 600 were epilepsy cases with at least 1 year of follow-up since epilepsy onset (median follow-up time: 5.8 years). There were 178 (30%) who had developed drug-resistant epilepsy, 353 (59%) who had been seizure free for ≥1 year, and 69 (12%) with intermediate seizure outcomes. Having an identified cause of epilepsy (genetic, structural, metabolic, or infectious) was associated with unsatisfactory seizure outcome (48% drug resistance) and influenced the relative risk associated with other prognostic factors. Sociodemographic characteristics were not associated with shortterm seizure outcomes.

CONCLUSIONS: Drug resistance occurs in 3 out of 10 children with epilepsy, whereas 6 out of 10 become seizure free. Having an identified cause of epilepsy is associated with poor response to treatment