Yamauchi 2006.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study in Japan Prospective pre‐randomisation baseline period: 12 weeks Treatment period: 12 weeks Dose‐reduction period lasting 8 days, 4 weeks instituted, followed by a 4‐week post‐dosing observation period 3 treatment arms, 1 placebo and 2 treatment
Participants	Adults aged ≥ 16 years Most aged 18‐44 years, mean age between 3 groups 31‐33 years Multicentre Japanese study from March 2000 to October 2002 Other AEDs: > 1 Total randomised 209 participants; all with drug‐resistant focal epilepsy 82 participants to placebo (42 men, mean age: 31.8 (SD 11.3) years, 25 secondary generalised seizures, mean duration epilepsy: 19.5 years, mean seizure frequency/28 days: 19.9, 1 other AED: 19.5%, 2 other AEDs: 80.5%) 86 participants to gabapentin 1200 mg (37 men, mean age 31.3 (SD 10.6) years, 26.3 secondary generalised seizures, mean duration epilepsy: 19.8 years, mean seizure frequency/28 days: 31.6, 1 other AED: 14%, 2 other AEDs: 86%) 41 participants to gabapentin 1800 mg (22 men, mean age 32.7 (SD 13.7) years, 13 secondary generalised seizures, mean duration epilepsy: 21.2 years, mean seizure frequency/28 days: 24.2, 1 other AED: 4.9%, 2 other AEDs: 95.1%) 19 excluded; after exclusion placebo: 75, gabapentin 1200 mg: 80, gabapentin 1800 mg: 35 Baseline seizure frequency/12 weeks: 8
Interventions	Gabapentin 1200 mg/day Gabapentin 1800 mg/day Placebo All treatments were identical in appearance (200 mg tablets)
Outcomes	Improvement in seizure frequency: completely (‐100%), markedly improved (‐99.9% to ‐75.0%), moderately improved (‐74.9% to ‐50%), slightly improved (‐49.9% to ‐25%), no change (‐24.9% to 0%), aggravated (> +0.1%) Response ratio (= (T ‐ B)/(T + B) where T = number of seizures during the treatment period, and B = number of seizure in the baseline period) Seizure intensity/duration: better, no change and worse Adverse effects Serious treatment‐related adverse effects
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Little/no detail regarding randomisation given. Most variables between groups controlled (age, sex, frequency, number of other AED, previous treatments etc.)
Allocation concealment (selection bias)	Unclear risk	Insufficient information provided
Blinding (performance bias and detection bias) All outcomes	Low risk	Tablets identical in appearance, all outcomes blinded, monitored and followed up in the same way
Incomplete outcome data (attrition bias) All outcomes	High risk	ITT analysis not employed; reasons for exclusions stated; however, 19 participants not included
Selective reporting (reporting bias)	Low risk	Seizure diary for all groups, same outcomes. Published reports include all prespecified expected outcomes
Other bias	High risk	Trial sponsored by Parke Davis Study appeared free of other sources of bias

AED: antiepileptic drug; EEG: electroencephalogram; ITT: intention‐to‐treat; SD: standard deviation; TDS: three times daily.