Forsythe 1991.

Methods	Single‐centre, randomised, parallel‐group trial conducted in the UK 3 treatment arms: CBZ, PHT, VPS
Participants	Children with at least 3 newly diagnosed generalised or partial seizures within a period of 6 months Number randomised: CBZ = 23, PHT = 20, VPS = 21 No information on epilepsy type or sex Age range: 5‐14 years
Interventions	Monotherapy with CBZ, PHT or VPS Mean dose: CBZ = 17.9 mg/d, PHT = 6.1 mg/d, VPS: 25.3 mg/d Trial duration: 12 months, range of follow‐up not stated
Outcomes	Cognitive assessments Summary of withdrawals from randomised drug
Notes	Outcomes chosen for this review were not reported IPD not available, but could be constructed from the publication for the outcome 'time to withdrawal of allocated drug'
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quota allocation by sex, age, seizure type and current treatment is an inadequate randomisation method
Allocation concealment (selection bias)	Unclear risk	No information provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	Personnel and participants (and parents) unblinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors single‐blinded for cognitive testing
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates reported, results reported and analysed for all participants randomised and all who completed various stages of follow‐up
Selective reporting (reporting bias)	Unclear risk	One of four outcomes for this review reported. Cognitive outcomes described in methods section well reported in results section. Adverse effects reported, no seizure outcomes reported and outcomes chosen for this review not reported. No protocol available so unclear if seizure outcomes were planned a priori
Other bias	Low risk	None identified