A Randomized, Double-Blind, Fixed-Dose Comparison of Paroxetine and Placebo in the Treatment of Generalized Social Anxiety Disorder

Background: This multicenter, double-blind, placebo-controlled study was carried out to determine the effectiveness and safety of various daily dosages of paroxetine for the treatment of generalized social anxiety disorder.

Method: A 1-week, single-blind, placebo run-in was followed by 12 weeks of double-blind treatment. 384 eligible patients meeting DSM-IV criteria for social anxiety disorder were randomly assigned to receive paroxetine, 20 (N=97), 40 (N=95), or 60 mg (N=97), or placebo (N=95) once daily in a 1:1:1:1 ratio. Primary efficacy variables included mean change from baseline in the Liebowitz Social Anxiety Scale (LSAS) total score and proportion of patients exhibiting a therapeutic response (defined as a Clinical Global Impressions-Global Improvement scale [CGI-I] score of 1 or 2).

Results: In the last-observation-carried-forward analyses, patients treated with paroxetine, 20 mg/day, had significantly greater improvement on mean LSAS total scores compared with those receiving placebo (p<.001), while the incidence of responders, based on the CGI-I rating, was significantly greater with paroxetine, 40 mg/day, than with placebo (p=.012). Patients treated with paroxetine, 20 and 60 mg, also had significantly better responses on the social item of the Sheehan Disability Scale than did patients treated with placebo (p<.019). The completer analyses showed a significant difference between the placebo group and the 20-mg and 40-mg paroxetine groups on LSAS total score and rate of response (p.006). There were no serious adverse experiences attributed to paroxetine treatment.

Conclusion: Paroxetine, 20 mg/day, is an effective and safe treatment for patients with generalized social anxiety disorder and significantly improves social anxiety, avoidance of social interactions, social disability, and overall clinical condition. Further data analyses are needed to determine whether more specific guidelines for paroxetine dosage escalation in social anxiety disorder can be drawn.