Brodie 2005.

Study characteristics
Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study Allocation concealment using telephone randomisation Random permuted blocks of 6 per participating centre Blinded using identical tablets and packaging 12 week pre‐randomisation baseline period, 24‐week treatment period including 6‐week dose titration
Participants	Multicentre study, 49 centres in Europe and 5 in South Africa 351 participants. At least 12 seizures during 12‐week baseline period, with no period of more than 3 weeks seizure‐free Taking 1 to 3 AEDs Aged 12 to 77 51% male
Interventions	Placebo, 100 mg, 300 mg, or 500 mg placebo, randomised in 2:1:1:2 ratio
Outcomes	Reduction in seizure frequency, proportion with a 50% or greater reduction in seizure frequency Adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Patients were randomised sequentially in blocks of six"
Allocation concealment (selection bias)	Unclear risk	Insufficient details were provided
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Treatments were blinded using a double dummy technique throughout the study"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient details about blinding of outcome assessors was provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	A modified ITT analysis was conducted as "all patients who received at least one dose of study drug were included in the safety analysis".  4 participants not included in the analysis were spread fairly evenly among groups (1 participant lost from 2 groups, 2 participants lost from 1 group)
Selective reporting (reporting bias)	Low risk	This study was deemed to be at a low risk of selective reporting
Funding Source	Low risk	Reported (sponsored by industry)
Conflicts of interest	Unclear risk	Not specified
Other bias	Low risk	Allocation to groups led to different durations of stable‐dose phase