Methods	Allocation: random, no further details. Blindness: double, identical capsules. Duration: 12 weeks. Design: parallel. Location: not reported.
Participants	Diagnosis: (DSM-IV or ICD-10) schizophrenia, predominant negative symptoms, CGI of 4 or more, PANSS negative subscore of 21 or more. N = 44. Sex: 27 M, 17 F. Age: mean quetiapine = 30.6 years, mean risperidone = 39.3 years. History: duration ill mean quetiapine = 5.4 years, mean risperidone = 2.5 years, age at onset mean quetiapine = 25.3 years, mean risperidone = 36.9 years. Setting: partially in- and outpatient.
Interventions	Quetiapine: flexible dose. Allowed dose range: 50-800 mg/day, Mean dose: 589.7 mg/day. N = 22. Risperidone: flexible dose. Allowed dose range: 2-8 mg/day. Mean dose: 4.9 mg/day. N = 22
Outcomes	Leaving the study early: any reason, adverse events, inefficacy. Mental State: PANSS total score, PANSS positive subscore, PANSS negative subscore, SANS total score. Cognitive functioning: auditory verbal memory test, Trail Making Test, Wechsler visual memory scale. Adverse effects: open interviews, cardiac effects (ECG), EPS (akathisia, parkinsonism, use of antiparkinson medication, SAS), sedation, headache, nausea, insomnia, dizziness, weight gain, laboratory (prolactin) Unable to use: SANS total score: no data. Prolactin change from baseline in ng/ml: no data. Cardiac effects: 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? subjective outcomes	Unclear risk	Double, identical capsules. Whether blinding was successful has not been examined, but both compounds differ quite substantially in side effects. This can be a problem for blinding
Blinding? objective outcomes	Low risk	Objective outcomes such as laboratory measures or death are unlikely to have been much affected by problems of blinding
Incomplete outcome data addressed? All outcomes	High risk	The overall attrition was high (45.2%). The data were analysed using both a LOCF method and a study completer approach. Nevertheless, it is questionable whether any statistical method can account for such a high attrition
Free of selective reporting?	High risk	Data on negative symptoms (SANS) and some adverse effects were not available
Free of other bias?	High risk	The study was sponsored by the manufacturer of quetiapine.