Social anxiety disorder, which is characterized by fear of social situations involving interactions or performance, affects as many as 13 percent of persons at some point in life. Selective serotonin reuptake inhibitors (SSRIs) are the recommended treatment. Multiple studies of various SSRIs have proved their effectiveness in the short-term treatment of acute social anxiety disorder. However, this disorder is a chronic condition that requires treatment for at least 12 months. Stein and colleagues studied the efficacy of paroxetine as a long-term therapy for social anxiety disorder.

The trial was a placebo-controlled, multi-center study with a single-blind acute treatment phase and a randomized, double-blind maintenance phase.Adults were eligible for the study if they met the criteria for social anxiety disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed.

After a one-week placebo run-in period, all patients received paroxetine for 12 weeks. After two weeks and at the participating investigators’ discretion, the initial dosage of 20 mg per day could be titrated upward in 10-mg increments every two weeks to a maximum of 50 mg per day. Patients whose Clinical Global Impression (CGI) severity of illness score decreased by at least 2 points during the acute treatment phase, resulting in a final score of 3 or less, qualified for randomization in the 24-month maintenance phase. The main outcome measure was the number of patients who relapsed during the maintenance phase.

Of the 437 patients who entered the acute treatment phase, 323 qualified for the maintenance portion of the trial, during which patients were randomized to receive paroxetine or placebo. Relapse occurred in significantly fewer patients in the paroxetine group than in the placebo group (14 percent versus 39 percent). At the end of the study, the patients who received paroxetine demonstrated significantly greater improvement on the CGI improvement scale. Paroxetine was well tolerated during the maintenance phase, with headache being the most commonly reported adverse effect.

The authors conclude that paroxetine is an effective and well-tolerated agent for the prevention of relapse in patients with social anxiety disorder. They support the recommendation to continue pharmacotherapy beyond four months.