Boas 1996.

Methods	Randomized, double‐blind, cross‐over study. Two treatment arms: 1 placebo, 1 lamotrigine. Five phases: baseline period = 12 weeks; treatment I = 12 weeks; washout I = 4 weeks; treatment II = 12 weeks; washout II = 4 weeks.
Participants	4 centre study from Denmark. 56 adults with refractory drug‐resistant partial seizures, aged from 16 to 65 years. 30 were allocated to lamotrigine and 26 to placebo during the first treatment phase. There were 27 men and 29 women. Maximum number of other AEDs = 3.
Interventions	Lamotrigine or placebo was added to the patients' existing AEDs. The dose of lamotrigine varied from 75 to 400 mg. Participants on valproate received lower doses.
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	Partcipants were 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. All treatments (tablets) and packaging were identical. Prepacked coded medication was dispensed by pharmacy.
Incomplete outcome data (attrition bias)	Low risk	No participants were excluded from analysis. 10 participants withdrew from the study; 8 randomised to lamotrigine and 2 to placebo. The reasons for exclusion were reported.
Selective reporting (reporting bias)	Low risk	All outcomes stated in methods section of paper were reported in the results. There was no protocol available to check a priori outcomes.
Other bias	Unclear risk	This study was sponsored by GlaxoSmithKline, the manufactures of LTG.