Liu 2003.

Methods	Allocation: randomised Blinding: open label Duration: 8 weeks (wash‐out period: 3‐7 days) Design: parallel Country: China
Participants	Diagnosis: CCMD‐3 schizophrenia n = 60 Sex: male only Age: not stated, but likely to be adult, as their illness onset age is reported as 25 ± 5.27 years History: mean duration of illness: 14.73 ± 5.59 years Setting: inpatient
Interventions	1. Sodium valproate + clozapine: valproate fixed dose of 600 mg/day. n = 30 2. Clozapine: dosage unclear. n = 30
Outcomes	Leaving the study early: acceptability/tolerability of treatment Clinical response: mental state (BPRS total) Unable to use: Adverse events: no information provided
Notes	All participants took clozapine+placebo during wash‐out No information about the dosage of clozapine provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomly assigned in a 1:1 ratio", p11596
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) Objective outcomes	Low risk	We don't think blinding causes significant bias in objective outcomes
Blinding of participants and personnel (performance bias) Subjective outcomes	High risk	No information about blinding provided, assume open‐label
Blinding of outcome assessment (detection bias) Objective outcomes	Low risk	We don't think blinding causes significant bias in objective outcomes
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	No information about blinding provided, assume open‐label
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Three and four participants left early from the experiment and control groups respectively. Valproate group: 3/30 = 10%, monotherapy group: 4/30 = 13.3%, no reason provided for people leaving the study early. They are not included in the final analysis. (p 11,596)
Selective reporting (reporting bias)	High risk	Adverse events not reported
Other bias	Low risk	None obvious