Comparative efficacy of antidepressants in preventing relapse in anxiety disorders - A meta-analysis

Background: We assessed the efficacy of continuation treatment with antidepressants in a meta-analysis of relapse prevention studies in the five principal anxiety disorders, to explore the benefit of continuation treatment in each disorder, and their relative efficacy across these disorders. Method: Double-blind placebo-controlled studies with relapse prevention designs in Panic Disorder, Generalized Anxiety Disorder, Social Phobia, Post-Traumatic Stress Disorder and Obsessive-Compulsive Disorder were identified in a systematic literature search. The primary efficacy comparison was relapse rates between active and placebo arms calculated as odds ratios (ORs) using Review Manager version 5.0. Relapse data were also used to calculate relative risk (RR), risk difference (RD) and number needed to treat (NNT). Results: Twenty-two relapse prevention trials were identified for these 5 disorders. Continuation antidepressant treatment produced robust treatment effects for each disorder, however the magnitude varied by indication. The greatest treatment effect was noted for GAD (pooled OR 0.20), whereas the pooled ORs for PD and OCD were for almost 2-fold higher (0.35 and 0.38 respectively). RR, RD and NNT showed similar statistically significant trends. Limitations: This study cannot identify an optimal duration of therapy. This analysis only examined studies testing monoamine reuptake inhibiting antidepressants, and therefore these results might not be generalizable to other classes of antianxiety agents. Conclusions: This meta-analysis underscores the importance of continuation treatment following acute response in all 5 anxiety disorders, however the relative efficacy of continuation antidepressant treatment appears to vary by disorder. (C) 2009 Elsevier B.V. All rights reserved.