French 2016.

Methods	Randomised, flexible dose, double‐blind, parallel‐group study 2 active treatment arms: 1 gabapentin and 1 pregabalin Multicentre study: 56 centres (Eastern and Western Europe, Asia South and Central America) 3 main phases: 6 weeks of baseline (screening), 9 weeks of double‐blind dose escalation (titration) and 12 weeks of double‐blind maintenance phase (21‐week treatment phase)
Participants	Adults with refractory focal epilepsy Inclusion criteria: aged 18‐80 years; diagnosis of epilepsy with focal‐onset seizures, inadequately controlled with ≤ 2 to ≥ 5 prior AEDs, receiving 1 or 2 standard AEDs (other than gabapentin or pregabalin), with a minimum of 4 focal‐onset seizures during the 6‐week baseline phase with no 28‐day focal‐onset‐seizure‐free period. 561 participants screened and 484 randomised: 242 to gabapentin and 242 to pregabalin Number of people who received intended treatment: 241 gabapentin and 241 pregabalin Number of people who completed the maintenance phase of the study: 172 gabapentin (69 discontinued treatment) and 187 pregabalin (54 discontinued treatment). Age (mean): gabapentin 35.3 (SD 12.9) years; pregabalin 34.9 (SD 13.0) years Age at epilepsy diagnosis (mean): gabapentin 19.9 years; pregabalin 19.8 years Time since diagnosis of epilepsy: gabapentin 15.8 years; pregabalin 15.6 years Sex of participants: gabapentin 130 men and 111 women; pregabalin 127 men and 114 women
Interventions	Intervention (241 participants): gabapentin (300 mg/day, 600 mg/day, 1200 mg/day, 1500 mg/day, 1800 mg/day); Active control (241 participants): pregabalin (150 mg/day, 300 mg/day, 450 mg/day, 600 mg/day). During the 9‐week dose‐escalation phase the minimum maintenance phase dose was gabapentin 1200 mg/day and pregabalin 300 mg/day TDS. During the 21‐week double‐blind phase of the study, the median doses were gabapentin 1500 mg/day and pregabalin 450 mg/day.
Outcomes	Seizure frequency: ≥ 50% reduction of seizures; ≥ 75% reduction of seizures Seizure freedom (for final 28 days) Withdrawals: any reasons and due to adverse effects Adverse effects (more common): somnolence, dizziness, headache, increased weight and dry mouth
Notes	Clinical Trials.gov ID NCT00537940
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation method used
Allocation concealment (selection bias)	Low risk	Randomised participants to either gabapentin or pregabalin (1:1)
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No details provided regarding blinding of study personnel, participants and outcome assessors
Incomplete outcome data (attrition bias) All outcomes	Low risk	242 participants allocated to gabapentin; 241 received treatment; 172 completed maintenance phase; 69 participants withdrew 242 participants allocated to pregabalin allocation; 241 received treatment; 187 completed maintenance phase; 54 participants withdrew The reasons for exclusion were reported.
Selective reporting (reporting bias)	Low risk	Protocol unavailable to check a priori outcomes, but appeared all expected and prespecified outcomes were reported
Other bias	High risk	Study funded by Pfizer Inc., the manufacturer of gabapentin and pregabalin Study appeared free of other sources of bias