Melancholic depression and response to quetiapine: A pooled analysis of four randomized placebo-controlled trials

Melancholic depression may preferentially respond to certain treatments. This study examined the efficacy of extended-release quetiapine monotherapy in patients with melancholic and nonmelancholic major depressive disorder.

Data from four randomized placebo-controlled trials was pooled. Melancholic features were assessed with baseline depression scale items according to DSM criteria. The outcome measure was response on the Montgomery-Åsberg Depression Rating Scale. Cox regression models predicting response over time with interactions between treatment condition and melancholic status were used to test for treatment effect heterogeneity.

The 6-week response rate difference between quetiapine and placebo was roughly 10% greater in the melancholic subgroup, primarily due to a lower placebo response, although the subgroup-treatment interactions did not reach statistical significance. The main effect of quetiapine was significant in every model.

The main limitations were the retrospective analysis and the post-hoc designation of melancholic depression based on scale items not designed for that purpose. Results should be considered preliminary and exploratory until replicated.

The lower placebo response rate in the melancholic subgroup is consistent with past research and reinforces the benefit of pharmacotherapy for these patients.