Retigabine (Adjunctive Therapy) Efficacy and Safety Study for Partial Onset Refractory Seizures in Epilepsy

28-day total PS (PSs [also called focal seizures] are seizures limited to a specific area of the brain) frequency in the BL period = (Number [No.] of total PSs reported in the BL period divided by the No. of days of available total PS data in the BL period) x 28 days. 28-day total PS frequency in the DB period = (No. of total PSs reported in the DB period divided by the No. of days of available total PS data in the DB period) x 28 days. Percent change = ([value in the DB period minus value at BL] divided by the BL value) x 100%. Negative values indicate a reduction in seizure frequency.

Responders were participants with at least a 50% reduction in the 28-day total partial seizure frequency in the Maintenance Phase as compared to the Baseline period.

Responders were participants with at least a 50% reduction in the 28-day total partial seizure frequency in the DB Phase as compared to the Baseline period. Participants without any post-baseline data were considered non-responders.

28-day total partial seizure frequency in the BL period = (No. of total partial seizures reported in the BL period divided by the No. of days of available total partial seizure data in the BL period) x 28 days. 28-day total partial seizure frequency in the Maintenance Phase = (No. of total partial seizures reported in the Maintenance Phase divided by the No. of days of available total partial seizure data in the same phase) x 28 days. Percent change = (value in the Maintenance Phase minus value at BL divided by the BL value) x 100%. Negative values indicate a reduction in seizure frequency.

Participants who experienced a reduction from Baseline in the 28-day total partial seizure frequency were categorized as having a reduction of 75-100%, 50-<75%, 25-<50%, or <25%, in addition to having no reduction. This quartile cutting was specified in the study protocol. Participants without any post-baseline data were included in the "No reduction" category.

Participants who experienced a reduction from Baseline in the 28-day total partial seizure frequency were categorized in decile cutting, i.e., reduction categories of 90-100%, 80-<90%, 70-<80%, 60-<70%, 50-<60%, 40-<50%, 30-<40%, 20-<30%, 10-<20%, >0-<10%, and increase categories of 0-10%, >10-20%, >20-30%, >30% (FDA endpoint). Participants without any post-baseline data were included in the 0-10% increase category.

Participants who experienced a reduction from Baseline in the 28-day total partial seizure frequency were categorized as having a >75%, a 50-75%, or a <50% reduction, in addition to having no reduction (EMEA endpoint).

Participants who experienced an exacerbation from Baseline in the 28-day total partial seizure frequency were categorized as having a 0-25% or a >25% increase (EMEA endpoint). The number of participants experiencing a >0% reduction from Baseline in the 28-day total partial seizure frequency are also presented.

New seizure types included those seizures which were not reported by any participant at Baseline.

Participants were considered to be seizure-free if they had not reported any seizures during the DB treatment period (Weeks 1-18). For a participant to be seizure free during the DB Phase, the participant had to be seizure free both Week 7 to Week 18 and Week 1 to Week 6. A participant could be seizure free Week 7 to Week 18 (during the Maintenance Phase), but not seizure free Week 1 to Week 6. Hence, there are fewer participants being reported as seizure free from Week 1 to Week 18 than from Week 7 to Week 18.

Participants were considered to be seizure-free if they had not reported any seizures during the Maintenance Phase.

A seizure-free day was a day without any seizures. For a participant to be seizure free during the DB Phase, the participant had to be seizure free both Week 7 to Week 18 and Week 1 to Week 6. A participant could be seizure free Week 7 to Week 18 (during the Maintenance Phase), but not seizure free Week 1 to Week 6. Hence, there are fewer participants being reported as seizure free from Week 1 to Week 18 than from Week 7 to Week 18. The percentage of seizure-free days was calculated as the total number of days without seizures in the DB period divided by the number of days in DB period x 100%.

A seizure-free day was a day without any seizures. The percentage of seizure-free days was calculated as the total number of days without seizures in the DB period divided by the number of days in the DB period x 100%.

Clinical Global Impression of Improvement (CGI-I) is a 7-point scale that requires the clinician to assess how much the participant's illness has improved or worsened relative to a baseline state at the beginning of the treatment. Scores on the scale are rated as: 1, very much improved; 2, much improved; 3, minimally improved; 4, no change; 5, minimally worse; 6, much worse; or 7, very much worse.

PGI is a participant-rated scale of improvement that was administered at the end of the Maintenance Phase in order to assess the participant's impression of his or her own improvement. PGI assessments were scored using a 7-point scale: 1, very much improved; 2, much improved; 3, minimally improved; 4, no change; 5, minimally worse; 6, much worse; or 7, very much worse.

The QOLIE-31-P is a 31-item questionnaire evaluating a participant's QOL perception in 7 domains: seizure worry, emotional well being, energy/fatigue, cognitive functioning, medication effects, social functioning, overall QOL. Precoded numeric values for some domains are such that a higher number reflects a more favorable health state; others are such that a higher number reflects a less favorable state. Precoded values are first converted to 0-100 point scores; higher converted scores always reflect better QOL. The overall score is derived by weighting and then summing the 7 domain scores.

Clinically important changes in laboratory values were to be reported as an adverse event if they met one of the following criteria: (1) intervention required; (2) change in dose of study drug required; (3) other treatment/therapy required; (4) association with other diagnoses.

A summary of the adverse events classified as renal or urinary disorders and in which at least 2% (rounded to an integer) of participants in any treatment arm reported during the study is presented.

Post-void residual (PVR) urine refers to the amount of urine remaining in the bladder after normal urination. To investigate the possible effects of retigabine on bladder function, all participants underwent post-void residual bladder ultrasound at Baseline and during the Maintenance Phase. The PVR bladder ultrasound was performed by a urologist, a qualified ultrasound technician, or a qualified study nurse who was certified to do PVR bladder ultrasound. Change from Baseline in PVR residual volume was calculated as the values at Week 10 and Week 18 minus the value at Baseline.

The number of participants with recorded weight gain of >=7% over their baseline weight was measured.