Predictors of response to pharmacotherapy in social anxiety disorder: an analysis of 3 placebo-controlled paroxetine trials

BACKGROUND: There is increasing evidence that patients with social anxiety disorder (social phobia) respond to treatment with selective serotonin reuptake inhibitors (SSRIs). Response rates to SSRIs in social anxiety disorder have ranged from at least 50% in controlled trials to up to 80% in open trials. To date, however, there has been little information available about predictors of response to treatment in this disorder. METHOD: Data from 3 placebo-controlled multicenter trials of paroxetine in DSM-IV social anxiety disorder (N = 829) were analyzed using logistic regression to determine predictors of response. Demographic (age, sex), physiologic (baseline heart rate, baseline mean arterial pressure), clinical (baseline social anxiety symptom severity, baseline disability, duration of illness), and trial variables (paroxetine dose, treatment duration) were included. RESULTS: Only duration of treatment was a statistically significant predictor of treatment response. Further analysis demonstrated that, in paroxetine-treated patients in particular, many nonresponders at week 8 (46/166; 27.7%) were responders at week 12. CONCLUSION: These data demonstrate that paroxetine is a reasonable choice of treatment in a broad spectrum of patients with social anxiety disorder. An optimal trial of medication should continue beyond 8 weeks.