Systematic Review: Retigabine for Adjunctive Therapy in Partial Epilepsy

• Responder Rate [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Proportion of patients who respond to treatment (50% reduction in seizure frequency from baseline)
• Median Seizure reduction [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Median percent reduction in seizure frequency from baseline
• Seizure severity [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Seizure severity (any definitions acceptable)
• Time to onset of treatment effect [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Time to onset of treatment effect
• Seizure free patients [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Proportion of patients who are seizure free (and time period over which this was measured)
• Changes in HRQoL [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Changes in HRQoL
• All drop outs [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: No ]
  Proportion of patients who drop out of the studies for any reason
• Drop outs due to AE [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: Yes ]
  Proportion of patients who drop out of the studies (as a result of adverse events i.e. tolerability)
• Adverse events [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: Yes ]
  Percentage of patients reporting 5 key adverse events identified by the Cochrane Epilepsy Group as common and important adverse effects of antiepileptic drugs: ataxia, dizziness, fatigue, nausea or somnolence
• Mortality [ Time Frame: Duration of studies included in the systematic review up to 28 weeks of double blind period ] [ Designated as safety issue: Yes ]
  Mortality

There are a number of anti-epileptic drugs available for the treatment of partial onset seizures in patients with epilepsy. This study is a systematic review of the published literature on anti-epileptic drugs and is designed to compare the relative effectiveness and tolerability of a selection of them with retigabine. The drugs chosen for this comparison were , lacosamide, pregabalin, tiagabine and zonisamide. They were chosen because they belong to the newer generation of drugs for epilepsy (as does retigabine) and they have a similar license as well as having published data from studies that were conducted in similar patient populations with similar methods. GSK commissioned YHEC (York Health Economic Consortium) to carry out this review and analysis. YHEC identified relevant studies from international databases. These studies had compared one of the chosen anti-epileptic drugs with placebo. The results were pooled and combined in order to summarise the data for individual drugs as well to compare the results for different drugs with each other and with retigabine. Since none of the individual clinical studies compared one active drug with another, this systematic review is an indirect comparison of these drugs, using an established and recognised methodology which has well understood limitations.

We included published papers on studies that had recruited drug-resistant (or refractory) partial epilepsy of all types

• Drug: retigabine/ezogabine
  oral - all doses
  Other Name: Trobalt (R); Potiga (R)
• Drug: lacosamide
  oral - all doses
  Other Name: Vimpat
• Drug: zonisamide
  oral - all doses
  Other Name: Zonegran
• Drug: pregabalin
  oral - all doses
  Other Name: Lyrica
• Drug: eslicarbazepine
  oral - all doses
  Other Name: Zebinix

Inclusion Criteria:

• Have participated to a study that meets the following criteria:
• Be a study of retigabine, eslicarbazepine, lacosamide, zonisamide, pregabalin or tiagabine as an adjuvant therapy, compared to placebo or another drug;
• Be a randomized, placebo-controlled, add-on trial, or a parallel trial or cross-over trial in which data from the first treatment period could be treated as a parallel study;
• Have recruited patients with drug-resistant partial epilepsy (i.e., simple partial, complex partial, and/or secondarily generalised tonic-clonic seizures not controlled by at least 1 or more other AEDs);
• Have a maintenance treatment period of 8 weeks or longer, with a prospective baseline of minimum 4 weeks.

Exclusion Criteria:

• N/A