We report the results from the first 12 months of a 2-year maintenance phase of a study evaluating long-term efficacy and safety of venlafaxine extended-release (XR) in preventing recurrence of depression.

Patients with recurrent unipolar depression (N=1096) were randomly assigned in a 3:1 ratio to 10-week treatment with venlafaxine XR (75 mg/d to 300 mg/d) or fluoxetine (20 mg/d to 60 mg/d). Responders (HAM-D17 total score ≤12 and ≥50% decrease from baseline) entered a 6-month, double-blind, continuation phase on the same medication. Continuation phase responders enrolled into the maintenance treatment period consisting of 2 consecutive 12-month phases. At the start of each maintenance phase, venlafaxine XR responders were randomly assigned to double-blind treatment with venlafaxine XR or placebo; fluoxetine responders continued for each period. Time to recurrence (HAM-D17 total score >12 and <50% reduction from acute phase baseline at 2 consecutive visits or the last visit prior to discontinuation) was evaluated using Kaplan-Meier methods and compared between groups using log-rank tests.

At the end of the continuation phase, venlafaxine XR responders were randomly assigned to venlafaxine XR (n=164) or placebo (n=172); 129 patients in each group were evaluated for efficacy. The cumulative probability of recurrence through 12 months was 23.1% (95% CI: 15.3, 30.9) for venlafaxine XR and 42.0% (95% CI: 31.8, 52.2) for placebo (P=0.005).

Twelve months of venlafaxine XR maintenance treatment was effective in preventing recurrence in depressed patients who had been successfully treated with venlafaxine XR during acute and continuation therapy.