Quetiapine as monotherapy for social anxiety disorder: A placebo-controlled study

Social anxiety disorder (SAD) is one of the most common anxiety disorders. Reports have suggested an effect of the atypical antipsychotic quetiapine in anxiety disorders. Given these considerations, we conducted a controlled trial of quetiapine monotherapy in SAD. Fifteen patients were randomized to quetiapine (up to 400 mg/day) or placebo for 8 weeks. The Brief Social Phobia Scale (BSPS) and the Clinical Global Impression of Improvement Scale (CGI-I) were the primary outcome measures, while the Social Phobia Inventory (SPIN) and the Sheehan Disability Inventory (SDI) were secondary measures. There was no significant difference on the BSPS score at endpoint between the quetiapine and placebo groups. There was a significant time effect but not a significant time × treatment group interaction, indicating that both the quetiapine and placebo patients did better over the course of the trial. 20% of the quetiapine patients had a 50% or greater drop in BSPS score at the end of the trial compared to baseline, while 0% had such a drop in the placebo group. There was no significant difference in responders (CGI-I score of 1 or 2) versus non-responder (CGI-I score of 3 or more) across the groups. However, 40% of quetiapine patients and 0% of the placebo patients showed much or very much improvement on the CGI-I. The Number Needed to Treat (NNT) to be a responder on the CGI-I was 3. Significant time effects were noted for the SPIN and SDI, as well as a significant time × treatment effect in favor of quetiapine on the SPIN. Additionally, quetiapine showed a large effect size on the SPIN.