AUTHOR=Denton Alyssa , Thorpe Lilian , Carter Alexandra , Angarita-Fonseca Adriana , Waterhouse Karen , Hernandez Ronquillo Lizbeth 

TITLE=Definitions and Risk Factors for Drug-Resistant Epilepsy in an Adult Cohort

JOURNAL=Frontiers in Neurology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.777888

DOI=10.3389/fneur.2021.777888

ISSN=1664-2295

ABSTRACT=Less than one-third of people with epilepsy will develop drug-resistant epilepsy (DRE). Establishing the prognosis of each unique epilepsy case is an important part of evaluation and treatment. Most studies on DRE prognosis have been based on a pooled, heterogeneous group including children, adults, and older adults in the absence of clear recognition and control of important confounders such as age group. Furthermore, previous studies were done before the 2010 definition of DRE by the International League Against Epilepsy (ILAE), so data based on the current definitions have not been entirely elucidated. This study aimed to explore the difference between three definitions of DRE and clinical predictors of DRE in adults and older adults. 
Methods
Patients with a new diagnosis of epilepsy ascertained at a Single Seizure Clinic in Saskatchewan, Canada were included if they had at least one year of follow-up. The first study outcome was the diagnosis of DRE epilepsy at follow-up using the 2010 ILAE definition. This was compared with two alternative definitions of DRE by Kwan & Brodie and Camfield & Camfield. Finally, risk factors were analyzed using the ILAE definition. 
Results
Ninety-five patients with a new diagnosis of epilepsy and a median follow-up of 24 months were included. The median age of patients at the diagnosis of epilepsy was 33 years, and 51% were males. In the cohort, 32% of patients were diagnosed with DRE by the Kwan & Brodie definition, 10% by Camfield & Camfield Definition, and 15% by the ILAE definition by the end of follow-up. The only statistically significant risk factor for DRE development was the failure to respond to the first anti-seizure medication (ASM). 
Conclusion
There were important differences in the percentage of patients diagnosed with DRE when using three concurrent definitions. However, the use of ILAE definition appeared to be the most consistent through an extended follow-up. Finally, failure to respond to the first anti-seizure medication was the sole significant risk factor for DRE in the cohort after considering the age group.