Leach 1997.

Methods	Double‐blind, random order, cross‐over, placebo‐controlled study in the UK 12 weeks' treatment or placebo No baseline period, however all participants reported at least 4 seizures/month for 3 months and AED doses had remained unchanged for ≥ 3 months prior to study
Participants	Single centre (Western Infirmary in Glasgow, UK) Adults with focal seizures refractory to 1 or 2 AEDs Total randomised: 27 participants; 23 analysed after withdrawals Aged 16‐67 years, mean 28.4 years 37% men prior to withdrawals
Interventions	3 sequential doses of gabapentin 400 mg, 600 mg and 800 mg TDS, each dose increase after 4 weeks) Placebo
Outcomes	Seizure frequency Seizure freedom Adverse effects (scored, individual adverse effects not mentioned) Neuropsychological tests (psychomotor, memory, cognition, dysphoria, temper, fatigue, worry, tiredness)
Notes	No baseline period, therefore not included in meta‐analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details of randomisation provided
Allocation concealment (selection bias)	Unclear risk	No details provided
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Double‐blind and matched placebo but no further details provided.
Incomplete outcome data (attrition bias) All outcomes	High risk	25% of participants excluded and not analysed on an ITT basis
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