Retention rates of antiepileptic drugs in glioma patients: the most appropriate outcome

Treatment with AEDs can be challenging in glioma patients as several aspects need to be considered: potential interactions between AEDs and chemotherapy (6), increased occurrence of adverse effects compared with nontumoral epilepsy patients receiving AEDs (7) and pharmacoresistance, in other words, failure to achieve seizure freedom even after AED dual therapy (8), in approximately20% of glioma patients (9). Here, we discuss different aspects regarding measuring AED outcomes in glioma studies: the difference between efficacy and effectiveness of AED treatment;why AED retention rate seems the most appropriate primary outcome in brain tumor related epilepsy studies;how the retention rate should statistically be analyzed and current literature on AED retention rates in glioma patients. The management of AED treatment in glioma patients is mostly done by either the treating neurologist or neurosurgeon and they see the glioma patient in regular follow-up visits every 3- or 6months, depending on the tumor grade. [...]a change in AED regimen and the reasons for this change are generally reported adequately in medical electronical records, supporting our belief that the retention rate is the most appropriate outcome in epilepsy studies. In studies estimating time to first seizure, or seizure freedom rates, in glioma patients (18), where a patients dies before the occurrence of a first seizure, KM’s methodology yields to bias as discussed previously. [...]to estimate the cumulative incidence of nonretention or first seizure, a competing risks model with death as competing risk must be used.