Methods	Allocation: random, no further details. Blindness: double, no further details. Duration: 8 weeks. Design: parallel. Location: single centre. Country: Italy.
Participants	Diagnosis: (DSM-IV) schizophrenia, treatment resistance to two previous antipsychotic medications, BPRS score of 27 or more. N=23. Age: 18 years or more (mean clozapine=38.3 years, mean olanzapine=34.1 years) (of completer population). Sex: 16 M, 7 F. History: duration ill not reported, age at onset not reported. Setting: inpatient.
Interventions	Clozapine: flexible dose. Allowed dose range: 300-400 mg/day. Mean dose: 325.4 mg/day. N=12. Olanzapine: flexible dose. Allowed dose range: 15-20 mg/day. Mean dose: 18.3 mg/day. N=11
Outcomes	Leaving the study early: any reason, adverse events, inefficacy. Mental State: PANSS total score, BPRS total score, PANSS positive subscore, PANSS negative subscore. Receptor occupancy measures ([18F]FESP/PET). Adverse effects: open interviews, EPS (SAS, AIMS). Unable to use - AIMS (no useable 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 the compounds differ quite substantially in side-effects. This can be a problem for blinding
Incomplete outcome data addressed? All outcomes	High risk	Numbers of leaving the study early were high (34.8%). The statistical analysis was based on completer data
Free of selective reporting?	High risk	Data on EPS scales were incompletely reported.
Free of other bias?	High risk	The study was sponsored by the manufacturer of olanzapine.