Rating 1999.

Study characteristics
Methods	Placebo‐controlled, parallel‐group, double‐blind randomised controlled trial Six‐month historical baseline followed by six‐month treatment phase
Participants	Participants between three and 10 years of age with a diagnosis of BECTS and at least two seizures in the past six months Number of participants randomly assigned: 66 Number of participants in each group: intervention group: 31 (16 [52%] males and 15 [48%] females); control group: 35 (24 [69%] males and 11 [31%] females) Median (range) age, years: intervention group: 8.2 (3.9 to 10.7); control group: 8.4 (3.1 to 10.3)
Interventions	Sulthiame (5 mg/kg/d) versus placebo
Outcomes	Adverse effects Proportion of participants in each group seizure free at six months Proportion of participants in each group experiencing a seizure during treatment period Proportion of participants withdrawing from treatment Proportion of participants withdrawing from treatment because of adverse effects Comparison of EEG prestudy and poststudy defined by the following groups No normalisation Transient normalisation Constant normalisation
Notes	31 participants (six from the intervention group and 25 from the control group) withdrew from the study Four participants from the intervention group withdrew because of seizure Two participants from the intervention group withdrew because of early termination of the study 21 participants from the control group withdrew because of seizure Two participants from the control group withdrew because of withdrawal of parental consent Two participants from the control group withdrew because of early termination of the study
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Provides partial explanation of how participants were allocated to each group. High proportion of males versus females in open group
Allocation concealment (selection bias)	Low risk	Provides clear explanation of how allocation was concealed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Provides clear explanation of blinding process
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Provides clear explanation of blinding process
Incomplete outcome data (attrition bias) All outcomes	High risk	Provides number of participants withdrawing from treatment but does not state whether intention‐to‐treat analysis was performed
Selective reporting (reporting bias)	High risk	No data on proportion of participants with a reduction in seizure frequency of 50% or greater, proportion of participants seizure free at 12 months or quality of life scale scores. Incomplete data on adverse effects
Other bias	Low risk	Inclusion and exclusion criteria clearly stated