Risk factors associated with drug resistant focal epilepsy in adults: A case control study

Using an adult cohort of patients with focal epilepsy, we aimed to identify risk factors for development of drug-resistant epilepsy, which if identifiable would allow patients to receive appropriate counsel and earlier surgical treatment.

This is a case-control study nested within a cohort, 146 adult patients with focal epilepsy were included. Definitions were used in accordance with ILAE criteria. The odds ratio and its confidence interval were calculated. We performed a logistic regression analysis.

Seventy-one [48.6%] patients met the criteria for drug-resistant epilepsy [cases] and 75 [51.4%] patients were controls. The mean age of patients was 44.5 ± 16.4 years. The most significant variables associated with developing drug-resistant epilepsy include younger age at diagnosis [18.75 vs. 32.2, p < 0.001], years of evolution of epilepsy [22.54 vs. 16.05, p < 0.001], number of AED [4.8 vs. 2.87, p < 0.001], complex partial seizures [51 vs. 35 OR 2.9, p = 0.002], having more than one seizure per month [51 vs. 38, p = 0.009], bi-temporal focus [14 vs. 4 p = 0.008] and mesial temporal sclerosis [23 vs. 11 p = 0.01]. Good response to first AED [7 vs. 29 OR 0.2, p = 0.001] and epilepsy secondary to encephalomalacia [8 vs. 20 OR 0.35, p = 0.018] might be protective factors against drug resistant epilepsy.

Longer time of epilepsy evolution, high frequency of seizures, complex partial seizure presentation, higher number of antiepileptic drugs, mesial temporal sclerosis and bitemporal epilepsy are predictive factors of subsequent pharmacoresistance.