P06. An Indirect Meta-Analysis of the Efficacy of Risperidone versus Olanzapine as Adjunctive Therapy for an Episode of Acute Mania in Bipolar I Disorder

Background: Risperidone and olanzapine are indicated in Australia for the short-term treatment of acute mania associated with bipolar I disorder.

Aim: The purpose of the present study was to compare the efficacy and safety of risperidone and olanzapine in bipolar I disorder.

Method: No head-to-head randomised controlled trials comparing the safety and efficacy of risperidone and olanzapine in the target population were identified. Therefore, data were extracted from randomised controlled trials of risperidone and olanzapine using placebo as the common comparator. The efficacy measures for risperidone and olanzapine were estimated using meta-analyses, and then compared using standard methods.

Results: Two randomised placebo-controlled trials of risperidone as adjunctive therapy to mood stabilizers in patients with current manic or mixed episodes associated with bipolar I disorder were identified. Both studies were of 3-week double-blind duration, followed by a 10-week open label treatment period. One randomised placebo-controlled trial of olanzapine as adjunctive therapy in the same target population was identified (6-week study duration). Using the Young Mania Rating Scale (YMRS), risperidone and olanzapine were more effective than placebo, however there was no significant difference between the two agents (calculated standardized mean difference (SMD) = −0.44 ± 0.13 (SE) for risperidone trials versus −0.45±0.12 for olanzapine; Z-statistic = 0.045, p = 0.96). The incidence of extrapyramidal symptoms and other adverse events was similar between risperidone and olanzapine.

Conclusion: Risperidone and olanzapine have similar efficacy in reducing mania, as measured by the YMRS. However, the short-term duration of these studies precludes an accurate comparison of the long-term safety profiles.