Matsuo 1993.

Methods	Randomised, double‐blind, parallel group, multi‐centre study. Three treatment arms: 1 placebo, 1 lamotrigine 300 mg and 1 lamotrigine 500 mg. Pre‐randomisation baseline = 12 weeks. Treatment phase = 24 weeks. Taper and follow‐up = 3 weeks.
Participants	Multicentre US study with 216 participants (67 males and 149 females) with a mean age of 33 (range 18 to 63) years. All had drug‐resistant partial epilepsy. 73 were randomised to receive placebo, while 71 received lamotrigine 300 mg per day and 72 received lamotrigine 500 mg per day. The mean duration of epilepsy was 21.9 years and the mean age at onset 11 years. Maximum number of other AEDs = 3. People receiving valproate were excluded.
Interventions	Add‐on lamotrigine 300 mg or lamotrigine 500 mg or placebo.
Outcomes	(1) 50% responder rates. (2) Withdrawal from study for any reason. (3) Adverse effects.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random permuted blocks.
Allocation concealment (selection bias)	Low risk	Randomisation concealment: allocated sequentially numbered, sealed packages containing either lamotrigine or placebo.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No details provided regarding blinding of participants, study personnel, and outcome assessors. Identical tablets and packaging used.
Incomplete outcome data (attrition bias)	Low risk	No participants were excluded from analysis. 25 participants withdrew from the study; 7 receiving lamotrigine 300 mg, 12 receiving lamotrigine 500 mg and 6 receiving placebo. The reasons for exclusion were reported.
Selective reporting (reporting bias)	Low risk	Protocol unavailable to check a priori outcomes, but appears all expected and pre‐specified outcomes were reported.
Other bias	Unclear risk	This study was sponsored by GlaxoSmithKline, the manufactures of LTG.