A validation of the new definition of drug-resistant epilepsy by the International League Against Epilepsy

OBJECTIVE

To establish applicability, the recently proposed International League Against Epilepsy (ILAE) consensus on drug-resistant epilepsy (DRE) requires testing in clinical and research settings. This study evaluates the reliability and validity of these criteria in a clinical population.

METHODS

In phase I, two independent evaluators reviewed 97 randomly selected medical records of patients with epilepsy at two separate intervals. Both ILEA consensus and standard diagnostic criteria were employed. Kappa, weighted kappa, and intraclass correlation coefficient (ICC) were used to determine interobserver and intraobserver variability. In phase II, ILAE consensus criteria were applied to 250 patients with epilepsy to determine risk factors associated with development of DRE and to calculate point prevalence.

RESULTS

The interobserver agreement of the four definitions was as follows: Berg (0.56), Kwan and Brodie (0.58), Camfield and Camfield (0.69), and ILAE (0.77). The intraobserver agreement of the four definition was as follows: Berg (0.81), Kwan and Brodie (0.82), Camfield and Camfield (0.72), and ILAE (0.82). The prevalence of DRE was the following: with the Berg's definition was 28.4%, Kwan and Brodie 34%, Camfield and Camfield 37%, and with ILAE was 33%.

SIGNIFICANCE

This is first study to establish reliability and validity of ILAE criteria for the diagnosis of DRE. This new definition compares favorably with previously established constructs, which continue to retain clinical significance.

Early predictors of remission in newly diagnosed epilepsy: a systematic approach to reviewing prognostic factor studies

BACKGROUND

It is necessary to select a range of consistently identified prognostic factors from exploratory studies to include in multivariate models of confirmatory studies. We illustrate a systematic approach to selecting consistently identified prognostic factors using the example of predictors of remission in newly diagnosed epilepsy.

METHODS

Medline and Embase were searched for reports of cohort studies enrolling at least 100 people with epilepsy within 1 year of diagnosis, and followed up for at least 1 year. We included studies that identified predictors of remission after adjusting for confounders using multivariate regression analysis. To identify consistent predictors a chart was designed to list the variables considered for inclusion in each model and those retained in more than one model from different cohorts were deemed to be consistent.

RESULTS

Remission off medication was less likely if there was more than one seizure between 6 and 12 months on medication and if there was comorbid intellectual disability in childhood onset epilepsy. The likelihood of remission on or off medication reduces with mixed seizure types at onset, intellectual disability, symptomatic aetiology, and also with increasing number of seizures before diagnosis or in the first 6 months after diagnosis.

CONCLUSION

A greater number of seizures before diagnosis and early in treatment, intellectual disability, and symptomatic aetiology are consistent predictors of less likelihood of remission. This suggests that early identification, diagnosis of epilepsy, and seizure control should be the primary aim of medical intervention, and that these predictors should be included in future confirmatory studies of prognostic factors of remission in newly diagnosed epilepsy.