Retention rates of new antiepileptic drugs in localization-related epilepsy: a single-center study

Objectives – We evaluated long‐term retention rates of newer antiepileptic drugs (AED) in adults with localization‐related epilepsy retrospectively. Methods – We estimated retention rates by Kaplan–Meier method in all 222 patients (age ≥ 16) with localization‐related epilepsy exposed to new AED at the Tampere University Hospital. Results – There were 141 patients exposed to lamotrigine, 78 to levetiracetam, 97 to topiramate, 68 to gabapentin, and 69 to tiagabine. Three‐year retention rate for lamotrigine was 73.5%, levetiracetam 65.4%, topiramate 64.2%, gabapentin 41.7%, and tiagabine 38.2%. The most common cause for withdrawal of these AED was lack of efficacy. Conclusions – Our study suggests that there are clinically significant differences among gabapentin, lamotrigine, levetiracetam, tiagabine, and topiramate as treatment for focal epilepsy in everyday practice. Gabapentin and tiagabine seem to be less useful than the other three AED. Furthermore, our study supports the value of retention rate studies in assessing outcome of the drugs in clinical practice.