Definition of drug-resistant epilepsy: A reappraisal based on epilepsy types

To re-assess the definition of drug-resistant epilepsy based on the evidence from a large-scale, long-term study including both adults and children. We categorized the patients as idiopathic generalized epilepsies (IGEs), focal epilepsies, or structural-metabolic-genetic generalized epilepsies [symptomatic generalized epilepsies (SGEs)] and provided the definition of drug-resistance based on the epilepsy types of the patients.

This was a longitudinal study of a prospectively developed and maintained database. All patients with an electro-clinical diagnosis of IGE, focal epilepsy, or SGE, who received treatment from 2008 to 2021, were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran. All patients had to be followed at our center for at least 24 months. The receiver operating characteristic curve (ROC curve) was used for the statistical analysis.

The included patients were as follows: 523 with focal epilepsy, 218 with IGE, and 211 with SGE. For all epilepsy types, the ROC curves of the number of appropriately prescribed antiseizure medications (ASMs) were acceptable indicators to anticipate drug-resistance. The best cutoff point for focal epilepsies was at 4 ASMs (sensitivity: 0.56, specificity: 0.81); for IGE, at 3 ASMs (sensitivity: 0.51, specificity: 0.80); and for SGEs, at 4 ASMs (sensitivity: 0.78, specificity: 0.58).

The definition of drug-resistant epilepsy should be different in various epilepsy types. It is the time for the scientific community to reappraise the definition of drug-resistant epilepsy in the light of the new evidence that has become available in the past 11 years since the previously published definition.