Two 6-week, double-blind, placebo-controlled studies evaluated quetiapine XR (QTP-XR) adjunct to ongoing antidepressant therapy in patients with MDD and an inadequate response to prior antidepressant treatment (D1448C00006/D1448C00007).

A post hoc pooled analysis examined clinical and demographic characteristics as potential predictors of response to adjunct QTP-XR

Pooled MITT population (n = 616 QTP-XR [both doses]; n = 303 placebo) data were analysed from the two adjunct QTP-XR (150 or 300 mg/day) studies.

Effects of psychiatric history and baseline demographic and disease characteristics on efficacy were evaluated in subgroups based on Week 6 MADRS total score reduction: ≥50% reduction (responders: n = 345 QTP-XR, n = 140 placebo) versus < 50% (non-responders: n = 271 QTP-XR, n = 163 placebo); ≥75% reduction (responders: n = 175 QTP-XR, n = 60 placebo) versus < 25% (non-responders: n = 125 QTP-XR, n = 89 placebo).

Impact of baseline CGI-S score and number of episodes (0, 1, 2–3, 4–10, ≥10) over previous year and lifetime on Week 6 MADRS total score change was evaluated. Effect of baseline MADRS individual item (1–10) scores on Week 6 change in CGI-I score was evaluated.

No major differences between responders and non-responders to QTP-XR were observed for patient characteristics. there was no predictive association between baseline CGI-S score, number of depressive episodes, and baseline MADRS item scores and efficacy outcomes for adjunct QTP-XR.

This pooled analysis showed no major differences between responders and non-responders, and no suggestion of a predictive association between the parameters assessed and efficacy outcomes for adjunct QTP-XR. Further investigation including logistic regression may be required.

AstraZeneca funded.