Sivenius 1991.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study in Finland 3 treatment arms: 1 placebo and 2 gabapentin Prospective pre‐randomisation baseline period: 12 weeks Treatment period: 12 weeks
Participants	All adults Total randomised: 45 participants; all with drug‐resistant focal epilepsy 18 placebo; 18 gabapentin 900 mg/day; 9 gabapentin 1200 mg/day 47% men Aged 16‐59 years Other AEDs: ≤ 2 Median baseline seizure frequency per 12‐week baseline period: 36 placebo; 26 gabapentin 900 mg/day; 23 gabapentin 1200 mg/day
Interventions	Gabapentin 900 mg/day Gabapentin 1200 mg/day Placebo All treatments and packaging were identical in appearance
Outcomes	Median change in seizure frequency % change in seizure frequency Adverse effects
Notes	2 people in the gabapentin 900 mg group were excluded from analysis, both excluded 2 weeks' postrandomisation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Allocated sequentially, sealed, numbered packages
Allocation concealment (selection bias)	Low risk	Random permuted blocks
Blinding (performance bias and detection bias) All outcomes	Low risk	Tablets and packaging identical in appearance. Identical analysis of results
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No reasons reported for exclusion of 2 participants in gabapentin 900 mg group
Selective reporting (reporting bias)	Low risk	Quote: "... seizure frequency was recorded" Unclear how, otherwise included all prespecified expected outcomes
Other bias	High risk	Trial sponsored by Parke Davis Study appeared free of other sources of bias