Beyond remission: rationale and design of the Prevention of Recurrent Episodes of Depression with Venlafaxine for Two Years (PREVENT) Study.

Recurrent major depressive disorder (MDD) is a common and disabling illness, but few studies have addressed long-term antidepressant treatment of recurrent MDD (ie, beyond 1 year of maintenance therapy) or compared the efficacy and safety of different antidepressant classes in this population. This article describes the rationale and design of a unique multi-phase trial in patients with recurrent MDD. The Prevention of Recurrent Episodes of Depression with Venlafaxine for Two Years (PREVENT) study is a large double-blind, randomized, multi-center trial designed to assess the long-term efficacy of venlafaxine extended release (ER) in the prevention of depressive recurrence. Approximately 1,100 adult outpatients with MDD and a history of >or=3 lifetime episodes (with at least two occurring in the past 5 years) were randomized to 10 weeks of acute-phase treatment with either venlafaxine ER 75-300 mg/day or fluoxetine 20-60 mg/day, followed by 6 months of continuation-phase treatment for patients experiencing a satisfactory therapeutic response or remission during the acute phase. Responders and remitters to continuation phase treatment were then entered into a 2-year maintenance phase study, in which those receiving venlafaxine ER were re-randomized to either venlafaxine ER or placebo at the start of two 12-month maintenance periods. Those taking fluoxetine during the acute and continuation phases continued to receive double-blind treatment with fluoxetine. This study will address several unanswered questions about the long-term treatment of recurrent MDD, such as whether extended maintenance treatment (ie, up to 2 years) lessens the risk for developing future depressive episodes; whether fluoxetine and venlafaxine ER are effective for both short- and long-term treatment of MDD; whether rates of tachyphylaxis differ between antidepressant classes; and whether the likelihood of depressive recurrence differs according to the time point when treatment is discontinued.