US Gabapentin 1993.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study in the US 4 treatment arms: 1 placebo and 3 gabapentin Prospective pre‐randomisation baseline period: 12 weeks Treatment period: 12 weeks
Participants	All adults USA study Total randomised: 306 participants; all with drug‐resistant focal epilepsy Placebo: 98 participants; gabapentin 600 mg/day: 53; gabapentin 1200 mg/day: 101; gabapentin 1800 mg/day: 54 66% men Aged 16‐70 years Other AEDs: ≤ 2 Median baseline seizure frequency/28 days: 10.8 (range 2.0‐1092.7)
Interventions	Gabapentin 600 mg/day Gabapentin 1200 mg/day Gabapentin 1800 mg/day Placebo All treatments and packages were identical in appearance
Outcomes	Proportion with a 50% reduction in seizure frequency Response ratio Adverse effects
Notes	18 participants excluded from published analyses: placebo: 3; gabapentin 600 mg/day: 4; gabapentin 1200 mg/day: 10; gabapentin 1800 mg/day: 1 Additional unpublished data allowed the inclusion of participants excluded despite completing the treatment phase with adequate seizure data. The following participants contribute to the best‐case and worst‐case sensitivity analyses in this review. Placebo: 2; gabapentin 600 mg/day: 4; gabapentin 1200 mg/day: 10; gabapentin 1800 mg/day: 1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Used random permuted blocks to generate sequence for randomisation
Allocation concealment (selection bias)	Low risk	Allocated sequentially, sealed, numbered packages
Blinding (performance bias and detection bias) All outcomes	Low risk	Used tablets and packaging identical in appearance
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition rate reported, 18 participants not included in published analyses and no reasons given
Selective reporting (reporting bias)	Low risk	Included all prespecified expected outcomes
Other bias	High risk	Trial sponsored by Parke Davis Study appeared free of other sources of bias