Continuation and long-term maintenance treatment with Hypericum extract WS 5570 after successful acute treatment of mild to moderate depression--rationale and study design.

Unipolar major depression is often a chronic disease that may require lifelong prophylaxis. Recovery from an acute episode is followed by 4-6 months of relapse prevention. After that, long-term maintenance treatment is administered to avoid recurrence. We present the rationale and design of an ongoing double-blind, randomized, placebo-controlled trial investigating the efficacy of Hypericum extract WS 5570 in relapse prevention in recurrent unipolar depression. An estimated sample of 425 adults with recurrent, mild to moderate major depression (ICD-10 and DSM-IV criteria), > or = 3 previous episodes (last 5 years) and a total score > or = 20 points on the 17-item Hamilton Rating Scale for Depression (HAMD) will be included. After a one-week wash out patients receive 3 x 300 mg/day WS 5570 single-blind for 6 weeks. Responders are randomized to 26 weeks of double-blind continuation treatment with 3 x 300 mg/day WS 5570 or placebo. Patients completing continuation treatment without relapse enter 52 weeks of doubleblind maintenance treatment, where those treated with WS 5570 are re-randomized to 3 x 300 mg/day WS 5570 or placebo. The primary outcome measure is the time to relapse during continuation treatment (HAMD > or = 16, clinical diagnosis of depression, or premature treatment termination for inefficacy). Hypericum extract, with its favourable tolerability profile, could be an interesting option for long-term prophylaxis. The trial was designed according to current consensus and guidance. Notably, it includes long-term prophylactic treatment with the same drug and the same therapeutic dose applied during acute treatment, uses well-defined outcome measures and provides a clear distinction between relapse and recurrence.