Methods	Allocation: random, no further details. Blindness: double, no further details. Duration: 8 weeks. Design: parallel. Location: single centre. Country: China.
Participants	Diagnosis:(CCMD-3) schizophrenia. N=61. Age: mean clozapine=30 years, mean olanzapine=25.8 years. Sex: 29 M, 32 F. History: duration ill mean=4.2 years, age at onset not reported. Setting: in- and outpatient.
Interventions	Clozapine: flexible dose. Allowed dose range: 25-400 mg/day. Mean dose: not reported. N=31. Olanzapine: flexible dose. Allowed dose range: 5-20 mg/day. Mean dose: not reported. N=30
Outcomes	Leaving the study early: adverse events. Mental State: BPRS total score. Adverse effects: open interviews, cardiac effects (palpitation, blood pressure), EPS, sedation, dry mouth, congestion, weight gain, laboratory (leukopenia) Unable to use - Leaving the study early - adverse events (no usable data). Leukopenia (no usable data).
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Random, no further details.
Allocation concealment?	Unclear risk	No further details.
Blinding? Objective outcomes	Low risk	Objective outcomes such as laboratory measures or death are unlikely to have been much affected by problems of blinding
Blinding? Subjective outcomes	Unclear risk	Double, no further details. Whether blinding was successful has not been examined, but both compounds differ quite substantially in side-effects. This can be a problem for blinding
Incomplete outcome data addressed? All outcomes	High risk	Data on leaving the study early were not provided.
Free of selective reporting?	High risk	Data were not available for all of the predefined adverse effect outcomes
Free of other bias?	High risk	The sponsor was unclear. The upper dose range limit of clozapine was 400mg/day which was reached rather quickly (10 days), which could mean a disadvantage for clozapine in terms of side effects