Chen 1998.

Methods	Allocation: randomly assigned (no further details). Blinding: not stated. Duration: six weeks. Setting: unclear.
Participants	Diagnosis: schizophrenia. N = 176. Age: 17 to 55 years. Sex: male and female (numbers not given) Racial origin: unclear. Consent: unclear. History: Average length of illness: 8 ± 11months.
Interventions	1. Clozapine: dose 200 mg/day. N = 94. 2. Clozapine: dose 500 mg/day. N = 82.
Outcomes	Global state: Clinically important response as defined by individual studies (BPRS score > 30% change). Mental state: average endpoint score and average change score B (BPRS‐A). Adverse effects: TESS scores, lethargy, hypersalivation, dizziness, tachycardia. Leaving the study early.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomly assigned, no further details.
Allocation concealment (selection bias)	Unclear risk	No details.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not stated.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All data reported; no loss to follow up.
Selective reporting (reporting bias)	Low risk	No indication of selective reporting.
Other bias	Unclear risk	Sponsor unclear.