Melancholic features in inpatients with major depressive disorder associate with differential clinical characteristics and treatment outcomes.

To determine whether the presence of melancholic features in hospitalized patients with major depressive disorder (MDD) was associated with specific clinical characteristics and treatment outcomes, supporting melancholic depression as a distinct subtype within MDD. 126 acutely ill inpatients with MDD were enrolled in an open, 6-week trial with fixed-dose fluoxetine 20mg daily. Symptom severity was assessed regularly, using the 17-item Hamilton Depression Rating Scale (HAMD-17) and Clinical Global Impression of Severity (CGI-S). Melancholic features were defined according to the DSM-IV criteria. Clinical variables were compared between patients with and without melancholic features. Generalized estimating equations method was used to explore the differences in HAMD-17 and CGI-S scores between the 2 groups over time. Clinical response was defined as having a 50% or greater reduction in HAMD-17 scores. 96 (76.2%) of the 126 patients with at least one post-baseline assessment met the criteria for melancholic depression. Melancholic depression differed from non-melancholic depression in clinical characteristics and predicted a better response to fluoxetine treatment. The differentiation between melancholic and non-melancholic depression within MDD hence is clinically significant and valid.