Cluster analysis of symptoms during antidepressant treatment with Hypericum extract in mildly to moderately depressed out-patients. A meta-analysis of data from three randomized, placebo-controlled trials

Rationale: Although extracts from Hypericum have long played a major role in the treatment of mild to moderate depression, information pertaining to the drug's therapeutic profile is sparse. Objectives: To investigate whether the administration of the Hypericum extract has a selective effect on particular signs and symptoms of depression as opposed to a more general acceleration of recovery. Methods: A meta-analysis was performed on the original data of three double-blind, randomized multicenter trials, during which 544 out-patients suffering from mild to moderate depression according to DSM-IV criteria received 3x300 mg/day Hypericum extract (WS(R) 5570 or WS(R) 5572) or placebo over a double-blind treatment period of 6 weeks. The primary outcome measure for treatment efficacy in the original trials was the change in the total score of the Hamilton Rating Scale for Depression (HAMD, 17-item version) between baseline and treatment end. The relationship between the symptoms of depression represented by the items of the HAMD was assessed by means of cluster analysis and individual item analysis. Results: Two clusters of items were identified which were stable in several independent subsets of the full data set. While cluster 1 (HAMD items 1, 2, 3, 7, 8, 12, 13, 14, 16) was interpreted to represent the core symptoms of depression (including somatic aspects), cluster 2 (items 4, 5, 6, 9, 10, 11, 15, 17) was primarily composed of items assessing depression-related anxiety and insomnia. In both clusters, Hypericum extract reduced the symptoms of depression more effectively than placebo. However, the herbal drug was particularly effective in the core symptoms of the disorder. Conclusions: The results indicate that Hypericum extract accelerated the recovery from depression in a rather general manner, by influencing all investigated signs and symptoms of the disease. The drug's therapeutic profile was thus found to be similar to the profile of selective serotonin reuptake inhibitors.