One-year outcomes in schizophrenia after switching from typical antipsychotics to olanzapine in Japan: an observational study

BACKGROUND: The purpose of this study was to assess the 1-year clinical, functional, and safety-related outcomes following a switch to olanzapine of at least one typical antipsychotic drug in the previous regimen in the treatment of patients of schizophrenia in Japan. METHODS: Using data from a large 1-year prospective, multicenter, naturalistic study of olanzapine for the treatment of schizophrenia in Japan, patients who were switched from any oral typical antipsychotic to olanzapine were identified. Mixed models for repeated measures, controlling for baseline demographics, were utilized to assess outcomes for clinical and functional measures. RESULTS: Of the 262 patients who switched from typical antipsychotics to olanzapine, 41% were outpatients and 59% were inpatients. Most of these patients were switched due to poor medication efficacy (71.0%) or medication intolerability (25.6%). Most patients (71.4%) completed the 1-year study. Clinically and statistically significant (P < 0.01) improvements were observed in patient illness severity and health-related quality of life, including improvements in global symptom severity and in positive, negative, depressive, and cognitive symptoms. Over half of the patients (58.3%) demonstrated a treatment response to olanzapine and 47.4% achieved symptom remission. Mean weight gain from baseline to endpoint was 2.31 ± 4.72 kg, with 30.4% of patients experiencing clinically significant weight gain (at least 7% of baseline weight). CONCLUSION: During this 1-year naturalistic treatment of schizophrenia patients in Japan, switching from typical antipsychotics to olanzapine resulted in significant improvements in patients’ clinical and functional outcomes. Approximately one-third of patients had clinically significant weight gain. These findings highlight the favorable benefit to risk profile of switching to olanzapine following failure on typical antipsychotics.