Methods	Allocation: random, no further details. Blindness: single, rater-blinded. Duration: 104 weeks. Design: parallel. Location: multicentre. Countries: USA, Canada, France, Italy, UK, Czech Republic, Hungary, Croatia, South Africa, Argentina, Chile
Participants	Diagnosis: (DSM-IV) schizophrenia (n=609) or schizoaffective disorder (n=371), high suicidal risk. N=980. Age: 18-65 years (mean=37.1 years). Sex: 602 M, 378 F. History: duration ill not reported, age at onset mean=24.7 years. Setting: in- and outpatient.
Interventions	Clozapine: flexible dose. Allowed dose range: 200-900 mg/day. Mean dose: 274.2 mg/day. N=490. Olanzapine: flexible dose. Allowed dose range: 5-20 mg/day. Mean dose: 16.6 mg/day. N=490
Outcomes	Leaving the study early: any reason, adverse events, inefficacy. Global state: CGI - of suicide severity. Mental State: depression Calgary depression scale, anxiety Covi anxiety scale. General functioning: scale of functioning. Service use: number of participants re-hospitalised. Adverse effects: death (any reason, suicide attempt, suicide, scale of suicidal thinking), cardiomyopathy, EPS (akathisia, rigor), sedation, seizures, weight gain, suicide ideation, depression, insomnia, dysarthria, salivary hypersecretion, dry mouth, drug abuse, alcoholism, laboratory (glucose, hematology). Unable to use - ESRS (no 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	Single, rater-blind. Whether blinding was successful has not been examined, but the compounds differ quite substantially in side-effects. This can be a problem for blinding
Incomplete outcome data addressed? All outcomes	Unclear risk	The number of participants leaving the study early was high (38.7%). It is unclear whether any statistical method can account for such a high attrition rate. Quote: “every effort was made to follow patients for study end points for the two years of evaluation, even after they formally discontinued using the study drug. Such information from retrieved drop-outs was included in the intent-to-treat analysis”. Numbers on “retrieved drop-outs” were not indicated
Free of selective reporting?	High risk	Data on ESRS scales were not available.
Free of other bias?	High risk	The study was sponsored by the manufacturer of clozapine. Quote: “patients were allowed to reenter the study if they desired”. Comment: The study is not free of other bias.