Time to all-cause treatment discontinuation of olanzapine compared to other antipsychotics in the treatment of schizophrenia: a systematic review and meta-analysis

Objective: This comprehensive review and meta-analysis compared the effectiveness of olanzapine and other antipsychotics in schizophrenia treatment, defining effectiveness as time to all-cause medication discontinuation (primary) and as all-cause treatment discontinuation rates. This study examined randomized clinical trials (RCTs) and observational non-interventional studies.

Experimental procedures: 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.

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.

Conclusion: Using a global measure of medication effectiveness (time to all-cause medication discontinuation), olanzapine appears to be more effective - in both RCTs and observational studies - than most SGAs and FGAs, except for clozapine.