Treatment-completion rates with olanzapine long-acting injection versus risperidone long-acting injection in a 12-month, open-label treatment of schizophrenia: indirect, exploratory comparisons

Abstract

BackgroundLittle is known about the comparative effectiveness of atypical antipsychotics in long-acting injection formulation. Due to the absence of head-to-head studies comparing olanzapine long-acting injection and risperidone long-acting injection, this study was intended to make exploratory, indirect, cross-study comparisons between the long-acting formulations of these two atypical antipsychotics in their effectiveness in treating patients with schizophrenia.MethodsIndirect, cross-study comparisons between olanzapine long-acting injection and risperidone long-acting injection used 12-month treatment-completion rates, because discontinuation of an antipsychotic for any cause is a recognized proxy measure of the medication’s effectiveness in treating schizophrenia. Following a systematic review of the literature, two indirect comparisons were conducted using open-label, single-cohort studies in which subjects were stabilized on an antipsychotic medication before depot initiation. The first analysis compared olanzapine long-acting injection (one study) with pooled data from nine identified risperidone long-acting injection studies. The second analysis was a “sensitivity analysis,” using only the most similar studies, one for olanzapine long-acting injection and one for risperidone long-acting injection, which shared near-identical study designs and involved study cohorts with near-identical patient characteristics. Pearson Chi-square tests assessed group differences on treatment-completion rates.ResultsComparison of olanzapine long-acting injection data (931 patients) with the pooled data from the nine risperidone long-acting injection studies (3950 patients) provided almost identical 12-month treatment-completion rates (72.7% versus 72.4%; P = 0.87). When the two most similar studies were compared, the 12-month completion rate for olanzapine long-acting injection was significantly higher than for risperidone long-acting injection (81.3% versus 47.0%; P < 0.001). However, any conclusions drawn from this comparison may be limited by differences in the studies’ geographic catchment areas.ConclusionUsing treatment-completion rates as a proxy measure of medication effectiveness, olanzapine long-acting injection did not differ significantly from risperidone long-acting injection when including all eligible studies. However, the findings of this exploratory analysis should be interpreted with caution, considering the methodological limitations of these indirect, cross-study comparisons.

Switching to olanzapine long-acting injection from either oral olanzapine or any other antipsychotic: comparative post hoc analyses

“…Given that poor adherence to oral antipsychotic therapy is a major problem in the long-term management of schizophrenia, 1 completion/discontinuation of treatment is recognized as a proxy measure of a medication’s effectiveness in treating schizophrenia. 12 – 14 In addition, measuring discontinuation is said to integrate “patients’ and clinicians’ judgments of efficacy, safety, and tolerability into a global measure of effectiveness that reflects their evaluation of therapeutic benefits in relation to undesirable effects”. 12 …”

“…Given that poor adherence to oral antipsychotic therapy is a major problem in the long-term management of schizophrenia, 1 completion/discontinuation of treatment is recognized as a proxy measure of a medication’s effectiveness in treating schizophrenia. 12 – 14 Thus, time to all-cause discontinuation, rate of discontinuation, and reasons for discontinuation were used as proxy measures of effectiveness. Disease severity measures included mean change in Positive and Negative Syndrome Scale (PANSS) total, positive, and negative scores 15 and mean change in Clinical Global Impression Severity (CGI-S) score.…”

Post-Injection Delirium/Sedation Syndrome in Patients Treated with Olanzapine Pamoate: Mechanism, Incidence, and Management

“…In an indirect cross-study comparison between OLAI and RLAI, treatment completion rates after 12 months were evaluated [27]. However, no results were provided regarding safety issues.…”

Cost-Utility Analysis of Depot Atypical Antipsychotics for Chronic Schizophrenia in Croatia

“…For OLZ-LAI, we used the rate from a large cohort (n ¼ 1906). Even though that rate was with oral drugs (which normally have lower adherence rates than do depots), we used that value of 80.2% because it was higher than the 72.7% rate in 931 patients found with the depot form by AscherSvanum et al [57], and was quite similar to the rates of other depot atypicals.…”