Quetiapine extended-release vs olanzapine for Japanese patients with bipolar depression: A Bayesian analysis

It is unknown whether there are differences in efficacy and safety between quetiapine extended-release, 300 mg/d (QUEXR300), and olanzapine, 5-20 mg/d (OLA), for Japanese patients with bipolar depression.

We conducted a Bayesian analysis of data from phase 3 studies in Japan of QUEXR300 and OLA. Outcomes were remission rate (primary), response rate, improvement on the Montgomery-Åsberg Depression Rating Scale and 17-item Hamilton Depression Rating Scale scores, discontinuation rate, and incidence of individual adverse events. We calculated the standardized mean difference (SMD) and the risk ratio (RR) and 95% credible interval (95% CrI) for continuous and dichotomous data, respectively.

There were no significant differences between QUEXR300 and OLA for any of the efficacy outcomes. QUEXR300 was associated with a higher incidence of somnolence than OLA (RR = 5.517; 95% CrI = 1.563, 19.787), while OLA was associated with greater increase body weight (SMD = -0.488; 95% CrI = -0.881, -0.089) and blood prolactin levels (SMD = -0.642; 95% CrI = -1.073, -0.213) than QUEXR300, and a greater decrease in high-density lipoprotein cholesterol levels (SMD = -0.408; 95% CrI = -0.785, -0.030) than QUEXR300.

Although the two drugs' efficacy did not differ, OLA increased the risk of metabolic syndrome and QUEXR300 the risk of somnolence. A large scale, long-term, head-to-head comparison study of QUEXR300 vs OLA for Japanese patients with bipolar depression is needed to confirm the results of the current study.