Methods | Allocation: random, computer-generated randomisation. Blindness: double, identical capsules. Duration: 26 weeks. Design: parallel. Location: multicentre. Country: not reported. |
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Participants | Diagnosis: (DSM-IV) schizophrenia (n=230), schizoaffective disorder (n=116), prominent negative symptoms. N=346. Age: mean olanzapine=41.67 years, mean quetiapine=40.45 years. Sex: 228 M, 118 F. History: duration ill mean olanzapine=17.57 years, quetiapine=17.78 years, age at onset mean olanzapine=24.16 years, quetiapine=22.59 years. Setting: outpatient. |
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Interventions |
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Outcomes | Leaving the study early: any reason, adverse events, inefficacy. Mental State: PANSS total score, PANSS positive subscore, PANSS negative subscore, SANS total score, depression (Calgary Depression Scale). General functioning: GAF, Case Manager Rating Scale, Patient Functioning Rating Scale. Quality of life: QLS total score. Adverse effects: Sedation, weight gain, laboratory (hematology, uric acid) Unable to use - Leukopenia (no useable data). Use of antiparkinson medication (no data). |
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Notes | ||
Risk of bias | ||
Bias | Authors’ judgement | Support for judgement |
Adequate sequence generation? | Low risk | Random, computer-generated randomisation. |
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, 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 |
Incomplete outcome data addressed? All outcomes |
High risk | The drop-out rate was high (54.9%). The last-observation-carried-forward method was used to account for people leaving the study early. It assumes that a participant who discontinued the study would not have had a change of his condition if he had remained in the study. This assumption can obviously be wrong, especially in case of high attrition |
Free of selective reporting? | High risk | Numbers of participants with antiparkinson medication or leukopenia were not indicated |
Free of other bias? | High risk | The study was sponsored by the manufacturer of olanzapine. |