Sachdeo 1997

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group study. Three treatment arms: one PLC, two TGB. Participants randomly assigned using ratio 1:1:1 in blocks of six Treatment periods = 12 weeks
Participants	Multi‐centre US study (26 centres) 318 participants (178 male) aged 12 to 71 years with drug‐resistant partial epilepsy were randomly assigned 107 to PCB, 106 to TGB 16 mg BID, 105 to TGB 8 mg QID Valproate allowed in combination with an enzyme‐inducing drug but not as monotherapy Median baseline four‐weekly complex partial seizures; frequency during baseline was as follows: PCB = 8.4; TGB 16 mg BID = 8.4; TGB 8 mg QID = 7.9
Interventions	Add‐on placebo, TGB 16 mg BID or TGB 8 mg QID
Outcomes	50% responder rates Treatment withdrawal Adverse effects
Notes	From the 318 people randomly assigned to the double‐blind phase, four were excluded from the intention‐to‐treat analyses. All 318 people were evaluated for adverse events. 47 people withdrew from the study: 10 receiving PLC; 16 receiving TGB 16 mg BID; 21 receiving TGB 8 mg QID
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Used ratio of 1:1:1 in blocks of six per study centre
Allocation concealment (selection bias)	Low risk	Used sequentially allocated sealed packages
Blinding (performance bias and detection bias) All outcomes	Low risk	Used identical packaging and medication
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates reported and intention‐to‐treat analysis employed
Selective reporting (reporting bias)	Low risk	All outcomes reported in methods section were reported in text; however no protocol was available for comparison of outcomes