Clinical and demographic predictors of improvement during duloxetine treatment in patients with major depression: an open-label study.

BACKGROUND AND OBJECTIVES: Currently evidence about clinical and demographic predictors of response to newer antidepressants such as duloxetine is limited. This study aimed to investigate whether a number of predictors, particularly co-morbid anxiety disorders and anxious depression, are associated with clinical improvement.
METHODS: One hundred and one outpatients suffering from major depression (MD) were treated with duloxetine and assessed at baseline and at weeks 2, 4 and 8 on the 21-item Hamilton Depression Rating Scale (HDRS) and at weeks 4 and 8 on the Clinical Global Impression-Severity (CGI-S) scale.
RESULTS: Patients with co-morbid panic disorder or obsessive-compulsive disorder showed slowed improvements at 2 and 4 weeks compared with patients without such co-morbidities; however, they showed slightly higher or similar improvements, respectively, at 8 weeks. Also, anxious MD patients showed higher improvements compared with non-anxious MD patients at all time points, with the difference between groups increasing over time. Several other predictors, such as co-morbid premenstrual dysphoric disorder and lifetime generalized anxiety disorder, were also identified.
CONCLUSION: Our results suggest that co-morbidity with an anxiety disorder could negatively influence improvement following duloxetine treatment in the short term but that such a difference could be reversed by 8 weeks. However, given that the study had several limitations, including the lack of a comparison group and a flexible dosage design, further research is needed to replicate and extend these findings.