A randomized, 1-year follow-up study of olanzapine and risperidone in the treatment of negative symptoms in outpatients with schizophrenia.

OBJECTIVE To evaluate the efficacy of olanzapine compared with risperidone in negative symptoms, after 1 year of treatment, in schizophrenic outpatients with prominent negative symptoms. METHODS This was a multicenter, randomized, monitored, open-label, parallel, dose-flexible, 1-year study of outpatients with schizophrenia (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria) with prominent negative symptoms (Scale for the Assessment of Negative Symptoms [SANS] summary score > or =10) previously treated with conventional antipsychotics. Patients were randomly assigned to treatment with an initial dose of olanzapine 10 mg/d or more (n = 120) or risperidone 3 mg/d or more (n = 115). The primary efficacy measure was the SANS summary score. Secondary efficacy measures included Scale for the Assessment of Positive Symptoms, Clinical Global Impression of Severity Scale, Calgary Depression Scale, and Social Functioning Scale. The response rate was defined as 30% or more of improvement in the SANS summary score. RESULTS The mean dose throughout the study was 12.2 mg/d (+/-5.8 mg/d) for olanzapine and 4.9 mg/d (+/-2.0 mg/d) for risperidone. At 1 year, olanzapine patients showed significantly higher improvement than risperidone patients on the SANS summary (P = 0.015) and on the affective flattening (P = 0.007) and avolition/apathy (P = 0.028) SANS subscales. There were also significant improvements in favor of olanzapine in the Scale for the Assessment of Positive Symptoms summary (P = 0.021), Clinical Global Impression of Severity (P = 0.008), and Social Functioning Scale total (P < 0.001) scores. The response rate was greater (P = 0.001) in the olanzapine cohort (69.2%) than in the risperidone cohort (48.7%). Olanzapine patients reported less extrapyramidal side effects but a higher incidence of clinically important body weight increase than risperidone patients. CONCLUSIONS Long-term treatment with olanzapine was associated with significantly better improvement in negative symptoms as compared with risperidone-treated schizophrenic outpatients with prominent negative symptoms.