Soares–Weiser K et al. – Using a global measure of medication effectiveness, olanzapine appears to be more effective – in both randomized clinical trials and observational studies – than most second–generation antipsychotics and first–generation antipsychotics, except for clozapine.Methods
- Schizophrenia studies that compared olanzapine with individual first- (FGAs) and/or second-generation antipsychotics (SGAs) were included in the meta-analyses.
- Hazard ratios (HR), risk ratios (RR), and their associated 95% confidence intervals were extracted for RCTs and observational studies.
- Sensitivity analyses assessed the impact of sources of funding, dose of olanzapine, and allocation concealment method on final results.
- There were 60 RCTs (N=33,360) and 27 observational studies (N=202,591) included.
- On time to all-cause medication discontinuation, olanzapine was significantly better than aripiprazole, quetiapine, risperidone, ziprasidone and perphenazine for RCTs and better than amisulpride, risperidone, haloperidol, and perphenazine for observational studies.
- There were no significant differences between olanzapine and clozapine in RCTs or observational studies.
- All-cause discontinuation rates in RCTs were significantly lower for olanzapine compared to all comparators except amisulpride and clozapine.
- In observational studies, olanzapine was less effective than clozapine.
- Industry-sponsored studies favored olanzapine when compared to haloperidol and perphenazine; higher dose of olanzapine favored quetiapine and perphenazine when compared to olanzapine; method of allocation concealment did not generally affect the results.