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Antidepressants equally effective across severity levels of social anxiety, OCD, PTSD

Results from an individual patient data metaanalysis demonstrated that antidepressants are equally effective for all severity levels of social anxiety disorder, OCD and PTSD, but for generalized anxiety disorder and panic disorder, the benefits are small at low severity level.

“[Individual patient data] is needed to provide better insight into whether initial severity is associated with antidepressant efficacy for anxiety disorders,” Ymkje Anna de Vries, PhD, department of psychiatry, University Medical Center Groningen, the Netherlands, and colleagues wrote. “Given the limitations of the available evidence (including dichotomization of outcomes and predictors, which leads to a significant loss of power) and the conflicting results, the question of whether initial severity moderates antidepressant efficacy for anxiety disorders, OCD and PTSD remains unanswered.”

Researchers used individual patient data from 29 trials (n = 8,979) to examine whether severity of these disorders influences the efficacy of antidepressants. Specifically, they utilized individual patient data from eight trials for generalized anxiety disorder, four trials for social anxiety disorder, four trials for OCD, three trials for PTSD and 10 trials for panic disorder to study the interactions between severity and treatment group.

In total, 5,323 participants were treated with antidepressant medication in the 29 trials. Analysis revealed that severity moderated antidepressant efficacy in patients with generalized anxiety disorder and panic disorder.

Using the Hamilton Anxiety Rating Scale, the investigators found that the antidepressant–placebo difference was 1.4 points (standardized mean difference [SMD] = 0.21; 95% CI, 0.4-2.5) for participants with mild generalized anxiety disorder, which increased to 4 or greater for participants with severe illness (SMD = 0.45; 95% CI, 3.4-4.6). For participants who had two panic attacks per 2 weeks at baseline, the estimated drug–placebo difference was 0.2 (95% CI, 0.2–0.3) in favor of antidepressants at week 10, which increased to 0.4 (95% CI, 0.3-0.6) for those who experienced 10 panic attacks per 2 weeks at baseline and 4.7 (95% CI, 3-6.4) for those who had 40 attacks per 2 weeks at baseline. No interaction was observed for social anxiety disorder, OCD and PTSD.

According to the authors, the antidepressant–placebo differences were 16.1 points on the Liebowitz Social Anxiety Scale (SMD = 0.59; 95% CI, 12.9-19.3), 3.4 points on the Yale–Brown ObsessiveCompulsive Scale (SMD = 0.39; 95% CI, 2.5-4.4) and 10.3 points on the Clinician-Administered PTSD Scale (SMD = 0.41; 95% CI, 6.9-13.6) across severity levels.

“We found that antidepressants are equally effective across the severity range generally included in clinical trials for [social anxiety disorder], OCD and PTSD,” de Vries and colleagues wrote. “For [generalized anxiety disorder] and [panic disorder], however, the benefits of antidepressants over and above placebo are small at low severity, and the tradeoff between benefits and risks may therefore be unfavorable for these patients.” – by Savannah Demko

Disclosures: The authors report no relevant financial disclosures.