Chadwick 1998

Methods	Randomised (partially), double‐blind, multicenter trial conducted at 25 sites in Europe, Australia, South Africa and Canada. 4 treatment arms: GBP (3 arms, 300 mg/d, 900 mg/d and 1800 mg/d) and CBZ. Dose of GBP was masked within the treatment arm but CBZ was given open‐label due to difficulties of blinding tablets and capsules and differing titration periods for the two drugs.
Participants	Participants with newly diagnosed partial epilepsy, with at least 2 unprovoked partial or generalised tonic clonic seizures in the 6 months prior to trial entry, who were AED naive or had received fewer than 2 weeks of AED therapy, which had to be discontinued before trial entry. Participants with a seizure recurrence after at least 2 years of remission were also eligible. Number randomised: CBZ = 74, GBP = 218 157 male participants (54%) 100% participants with partial epilepsy Mean age (range): 35 (12‐86 years)
Interventions	Monotherapy with GBP or CBZ Titration period of 7 d for GBP to target doses 300 mg/d, 900 mg/d or 1800 mg/d. Titration period of 21 d for CBZ to target dose 600 mg/d. Titration period followed by an evaluation period of 24 weeks and an optional open‐label period Range of follow‐up: 0‐77 months
Outcomes	Time to exit Time to exit event plus withdrawals because of adverse events Completion rate (percentage of participants attending end‐of‐phase visit) Exit event rate (percentage of participants who experienced an exit event during the evaluation phase) Adverse event withdrawal rate (percentage of participants who withdrew because of adverse events during either titration or evaluation phases) Exit plus adverse event withdrawal rate (the sum of the exit rate plus the adverse event withdrawal rate) Incidence of adverse events
Notes	IPD provided for all outcomes of this review by trial sponsor Pfizer. In primary analysis, three arms of GBP are pooled and compared to CBZ (see Data extraction and management)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A randomisation schedule was prepared separately for each trial centre in blocks of four and eight
Allocation concealment (selection bias)	Low risk	Trial medication was distributed centrally via a pharmacy
Blinding of participants and personnel (performance bias) All outcomes	High risk	The trial was partially double‐blinded (the dose of GBP was blinded but GBP was not blinded compared to CBZ). Given that the main comparison made in this review is GBP compared to CBZ rather than comparisons between the doses of GBP, this trial is be treated as an open‐label trial
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not specifically stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates reported, ITT approach, all randomised participants analysed from IPD provided (see footnote 2)
Selective reporting (reporting bias)	Low risk	All outcomes reported or calculated with IPD provided (see footnote 2)
Other bias	Low risk	None identified