Vortioxetine versus placebo in major depressive disorder comorbid with social anxiety disorder

Major Depressive Disorder (MDD) and Social Anxiety Disorder (SAD) are highly comorbid, yet the combined condition has not been subject to any placebo-controlled treatment trials. This study reports a trial of vortioxetine, an antidepressant that has also shown benefit in Generalized Anxiety Disorder (GAD), in patients meeting DSM-5 criteria for both MDD and SAD.

The study was a 12-week double-blind, placebo-controlled comparison of vortioxetine 10-20 mg/day or placebo administered on a 1:1 ratio. The study was designed to include 40 male or female outpatients aged 18-70 years. The primary endpoint was the "composite" Clinical Global Impression of Improvement (CGI-I) responder rate, factoring in improvement in both MDD and SAD features. Major secondary outcome measures were changes on the Montgomery Asberg Depression Rating Scale (MADRS) and Liebowitz Social Anxiety Scale (LSAS).

On the composite CGI-I, 10 of 20 (50%) vortioxetine and six of 20 (30%) placebo-treated patients were rated as responders, a non-significant difference. However, vortioxetine-treated patients did show significantly greater improvement than those on placebo on both the MADRS (effect size 0.672) and LSAS (effect size 0.714). Efficacy in depression was seen before improvement in SAD. Adverse effects were similar to those previously reported.

In this preliminary trial vortioxetine appears safe and effective for patients with MDD comorbid with SAD, with robust effect sizes on dimensional measures of both depression and social anxiety, but failure to separate from placebo on the primary outcome measure of composite responder rate. More studies of patients with comorbid conditions are needed, as this mirrors what is often seen in clinical practice.