Turnbull 1985.

Methods	Single‐centre, parallel‐design RCT conducted in Newcastle, UK 2 treatment arms: PHT and VPS
Participants	Participants with ≥ 2 partial or generalised tonic‐clonic seizures in the past 3 years. Participants were previously untreated but started on AED treatment within 3 months of their most recent seizure Number randomised: PHT = 70, VPS = 70 73 male participants (52%) 63 participants with partial epilepsy (45%) Mean age (range): 35 (14‐70 years)
Interventions	Monotherapy with PHT or VPS Starting doses: PHT 300 mg/d, VPS 600 mg/d. Dose achieved not stated Range of follow‐up: 3.5‐52 months
Outcomes	Time to 2‐year remission Time to first seizure Adverse events
Notes	IPD provided for all outcomes included in this review by trial author
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants randomised with stratification for age group, gender and seizure type. Method of randomisation not stated or provided by author
Allocation concealment (selection bias)	Unclear risk	No information provided
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information provided
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided
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