UK Gabapentin 1990.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study (cross‐continent) Prospective pre‐randomisation baseline period: 12 weeks Treatment period: 14 weeks
Participants	All adults Cross‐continent study Total randomised: 127; all with drug‐resistant focal epilepsy Placebo: 66 participants; gabapentin 1200 mg/day: 61 participants 39% men Age range: 14‐73 years Other AEDs: ≤ 2 Median baseline seizure frequency/28 days: gabapentin 13 (range 3 to 368); placebo 13 (range 1 to 216)
Interventions	Gabapentin 1200 mg/day Placebo All treatments and packaging identical in appearance
Outcomes	Proportion with a 50% reduction in seizure frequency Response ratio Adverse effects
Notes	14 participants excluded from published analyses: 5 from the placebo group; 9 from the gabapentin 1200 mg/day group Additional unpublished data allowed the inclusion of participants excluded despite completing the treatment phase with adequate seizure data.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 1200 mg: 8
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, 14 participants who withdrew were not included in published analyses. Report withdrawals and gave reasons for withdrawal.
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