Effects of Treatment of Acute Major Depressive Episodes in Bipolar I Versus Bipolar II Disorders With Quetiapine

Background Several second-generation antipsychotic drugs (SGAs) have evidence of benefit for acute major depressive episodes in bipolar disorder (BD) patients. However, their comparative efficacy in types I vs II BD (BD1 vs BD2) remains uncertain. Methods We carried out a systematic literature search for randomized, double-blinded, controlled treatment trials for acute major depressive episodes involving head-to-head comparisons of BD1 versus BD2 subjects, followed by meta-analyses and meta-regression modeling. Results Seven reports met out inclusion criteria, yielding 22 comparisons of SGA versus placebo averaging 8.3 weeks in duration. All trials involved quetiapine, which was much more effective than placebo (pooled standardized mean difference [SMD] = 1.76 [95% confidence interval, 1.40-2.12], P < 0.0001). Estimated % improvement averaged 53.5% [46.5-60.5] with quetiapine vs 39.8% [34.2-45.4] with placebo (P < 0.0001); their ratio was somewhat larger with BD1 (1.56 [1.26-1.86]) versus BD2 subjects (1.22 [1.07-1.37], P = 0.04; as was SMD (BD1: 2.35 [1.83-2.86]; BD2: SMD = 1.44 [1.05-1.82]). Meta-regression found diagnosis (BD1 > BD2) to be the only factor significantly associated with the meta-analytic outcome. Conclusions Although data are limited, depressed BD1 patients may respond somewhat better to quetiapine than BD2. Additional head-to-head diagnostic comparisons are needed with other SGAs, as well as evaluation of monotherapy versus various combinations that include SGAs in both short- and long-term use.