Analysis of potentially predictive factors of efficacy of adjunct extended-release quetiapine fumarate in patients with major depressive disorder

Identification of predictors of treatment response in patients with major depressive disorder (MDD) may facilitate improved disease management. Data were pooled from two 6-week, double-blind, placebo-controlled studies of extended-release quetiapine (quetiapine XR; 150 or 300 mg/day) as adjunct to ongoing antidepressant therapy. Effects of psychiatric history and baseline demographic and disease characteristics on efficacy outcomes (Week 6 Montgomery Åsberg Depression Rating Scale [MADRS] total score reduction) were evaluated in population subgroups (quetiapine XR both doses pooled, n = 616; placebo, n = 303). Baseline Clinical Global Impressions-Severity (CGI-S) score and previous depressive episodes on Week 6 MADRS total score change, and baseline MADRS individual item scores on Week 6 change in CGI-Improvement score, were also evaluated. No major differences between responders and non-responders to quetiapine XR were observed for patient characteristics or demographic and disease characteristics. No suggestion of a predictive association was found between baseline CGI-S score, number of depressive episodes, and baseline MADRS item scores and efficacy outcomes. These analyses showed no major differences between responders and non-responders, and no predictive association between the parameters assessed and efficacy outcomes for adjunct quetiapine XR in patients with MDD and an inadequate response to prior antidepressant therapy.