Prognostic factors affecting long-term retention of topiramate in patients with chronic epilepsy

To determine the long-term retention rate of topiramate (TPM) therapy in patients with chronic epilepsy and to identify the relevant prognostic factors that influence retention.

All patients with chronic epilepsy (n = 393) prescribed TPM between October 1, 1995, and December 31, 1998, at a tertiary referral centre for epilepsy were analysed. The retention rate for TPM was calculated by using Kaplan-Meier survival analysis, and the prognostic factors influencing retention were analysed by using Cox regression.

Of patients prescribed TPM, 30% continued taking the drug beyond 3 years. Discontinuation was mainly due to adverse events and lack of efficacy. Use of more than one new concurrent antiepileptic drug (AED) and lower maximal daily doses were more likely to result in treatment discontinuation due to adverse events. Older age at onset of epilepsy, a history of having previously taken more than one new AED [lamotrigine (LTG), gabapentin (GBP), or vigabatrin (VGB)], and lower maximal daily doses were more likely to lead to discontinuation due to lack of efficacy.

A third of patients with chronic epilepsy started on TPM therapy will continue on treatment for >3 years. Absence of learning disabilities, late age at onset of seizures, previous use of more than one new AED, two or more concurrent AED use, and low maximal daily doses of TPM are more likely to result in discontinuation of medication. These factors should be taken into account when considering the use of TPM for the treatment of chronic epilepsy.