Objective: To evaluate relapse rates and predictors of relapse in 2 randomized, placebo-controlled trials of desvenlafaxine for major depressive disorder (MDD).
Method: Study 1: week 8 responders to open-label desvenlafaxine 50 mg/d entered a 12-week open-label stability phase. Patients with a continuing, stable response at week 20 were randomly assigned to 6-month, double-blind treatment (desvenlafaxine 50 mg/d or placebo). Study 1 was conducted between June 2009 and March 2011 at 87 sites worldwide. Study 2: week 12 responders to open-label desvenlafaxine 200 or 400 mg/d were randomly assigned to 6-month, double-blind treatment (desvenlafaxine 200 mg/d, 400 mg/d, or placebo). Study 2 was conducted between June 2003 and August 2005 at 49 sites in Europe, the United States, and Taiwan. Relapse was assessed separately by study with log-rank test using protocol definitions of relapse and with 17-item Hamilton Depression Rating Scale (HDRS-17) score ≥ 16 at any time during the double-blind phase. Kaplan-Meier estimates evaluated time to relapse, censoring data at months 1, 2, and 3 and overall; treatments were compared using hazard ratios. Cox proportional hazards models assessed relapse predictors.
Results: Overall relapse rates for all definitions were significantly lower for desvenlafaxine versus placebo for both studies (all P ≤ .002). In study 1, rates were significantly lower for desvenlafaxine versus placebo at month 2 (P = .016) and month 3 (P = .007) using the protocol definition. In study 2, relapse rates were significantly lower for desvenlafaxine versus placebo at months 1, 2, and 3 for both definitions (P < .0001-.002). Hazard ratios were similar at months 1, 2, and 3 and overall for both studies (0.382-0.639).
Conclusions: Desvenlafaxine 50 to 400 mg/d effectively prevented relapse at 6 months. Desvenlafaxine significantly prevented relapse early (month 1) versus placebo only in study 2.