Generalized anxiety disorder (GAD) is a chronic disorder in need of reliable data to guide long-term treatment.
To assess the benefits of 6 and 12 months' treatment of GAD with venlafaxine hydrochloride extended release (XR) in patients who improved after 6 months' open-label venlafaxine XR treatment.
After 6 months' open-label venlafaxine XR treatment, improved patients were randomized to venlafaxine XR or placebo for 6 months. All venlafaxine XR patients still in the study at 12 months were randomized to receive venlafaxine XR or placebo, and all placebo patients continued taking placebo for another 6 months.
One urban site (5 locations).
Of 268 patients with a diagnosis of GAD entering the open-label venlafaxine XR treatment phase, 158 (59.0%) completed 6 months, and 136 (50.7%) entered relapse phase 2 (6-12 months). Fifty-nine (43.4%) of 136 patients entered phase 3 (12-18 months).
Six months' open-label treatment with venlafaxine XR, followed by double-blind venlafaxine XR or placebo for 2 relapse phases, each lasting 6 months.
Main Outcome Measures
Time to relapse while receiving venlafaxine XR or placebo after 6 and after 12 months of treatment. Relapse was strictly defined to safeguard against assigning patients with venlafaxine XR discontinuation symptoms or temporary anxiety increase as relapse.
For objective 1, relapse rates in phase 2 (months 6-12) were 9.8% on venlafaxine XR and 53.7% on placebo (P < .001). For objective 2, relapse rates after 12 months on placebo (32.4%) were lower than after 6 months on venlafaxine XR (53.7%) (P < .03).
Treatment of GAD with an antidepressant should be continued for at least 12 months. Preliminary data demonstrate that improved patients who relapse while off their antianxiety medication after at least 6 months of treatment will again most likely respond to a second course of treatment with the same medication.
clinicaltrials.gov Identifier: NCT00183274.