Randomized placebo-controlled trial of escitalopram and venlafaxine XR in the treatment of generalized anxiety disorder

Abstract

Generalized anxiety disorder (GAD) is a highly prevalent and disabling condition. Escitalopram and venlafaxine extended release (XR) both are indicated for the treatment of GAD. Outpatients (ages 18-65 years) with DSM-IV-defined GAD (Hamilton Anxiety Scale [HAMA] >or=20) were eligible to participate in this randomized, double-blind, placebo-controlled, multicenter, flexible-dose trial. Following randomization, patients received 8 weeks of double-blind treatment with escitalopram (10-20 mg/day; N=127), venlafaxine XR (75-225 mg/day; N=129), or placebo (N=136). The primary efficacy parameter was mean change from baseline at week 8 in HAMA total score, using the Last Observation Carried Forward (LOCF) approach. Secondary efficacy parameters were HAMA psychic anxiety subscale, Clinical Global Impressions of Severity (CGI-S) and Improvement (CGI-I) scales. Treatment was completed by 77% of patients. The least square mean difference for change from baseline at week 8 in HAMA total score for escitalopram and venlafaxine XR versus placebo were -1.52 (P=.09) and -2.27 (P=.01), respectively, for LOCF, and -1.92 (P=.033) and -3.02 (P=.001), respectively, for Observed Cases (OC). On all secondary parameters, both active treatments were significantly superior to placebo on the LOCF and OC analyses. Discontinuation due to adverse events was not different for escitalopram versus placebo (7 versus 5%, P=.61), but was significantly greater for venlafaxine XR (13%) versus placebo (P=.03). Venlafaxine XR, but not escitalopram, separated from placebo on the primary efficacy measure, using the LOCF approach. However, overall efficacy analyses suggest that escitalopram and venlafaxine XR are both effective treatments for GAD. Escitalopram was better tolerated.