|St. John's Wort and the treatment of mild to moderate depression: a systematic review
|Clement K, Covertson C R, Johnson M J, Dearing K
The review concluded that St. John's Wort was effective for the treatment of mild to moderate depression in comparison with placebo and equivalent to taking pharmaceutical antidepressants. However, the small sample sizes, variations between studies and failure to report levels of statistical significance mean that the results may not be reliable.
To evaluate the efficacy of St. John's Wort (SJW) for the treatment of mild to moderate depression.
MEDLINE, PubMed, CINAHL, AltHealthWatch and the Cochrane CENTRAL Register were searched from 1998 to 2004 for studies reported in the English language; the search terms were reported. The bibliographies of articles were also screened for relevant studies.
Randomised controlled trials (RCTs) comparing SJW with one or two parallel treatments for participants with mild to moderate depression were eligible for inclusion. Studies of adolescents, pregnant or lactating women were excluded, as were participants with severe depression or suicidal ideations. In the included studies, SJW was compared with pharmaceutical antidepressants such as imipramine (75 mg twice daily), fluoxetine (20 mg/day), sertraline (50 mg/day) or placebo. The dosing schedule of SJW ranged from once to three times daily and total dosages ranged from 300 to 900 mg/day. The duration of treatment varied from 6 to 24 weeks. Diagnoses of depression in the included studies were made by reference to clinical history and by the use of evaluation tools such as the Hamilton Depression Rating Scale (HAM-D), the Clinical Global Impressions scale and the Depression scale. Outcomes in the included studies were only reported in terms of the HAM-D scale. The participants were aged from 18 to 70 years. Where gender ratios were reported, the percentage of females was higher than males.
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality
The Boyack and Lookinland Methodological Quality Index (MQI) was used to assess methods, outcomes, treatment effect, magnitude or reported differences, and a summary to determine study design and methodological quality. The MQI evaluation produces a percentage score relative to the Consolidated Standards of Reporting Trials (CONSORT) criteria for adherence to RCT study quality guidelines. The maximum score possible appeared to be 100%.
Two reviewers independently assessed validity and resolved any discrepancies through consensus.
Two reviewers independently extracted the data and resolved any discrepancies through consensus.
Methods of synthesis
The studies were combined in a narrative, with accompanying tables.
Results of the review
Six double-blind RCTs (n=977) were included in the review.
The average MQI score for the included studies was 56% (range: 46 to 66).
SJW was reported to be effective in reducing mild to moderate depression. Participants taking SJW showed a greater decrease in the HAM-D score when compared with placebo (1 RCT, n=72), with a reduction from 19.7 (± 3.4) to 8.9 (± 4.3) for the SJW group and from 20.1 (± 2.6) to 14.4 (± 6.8) for the placebo group. However, decreases in the HAM-D score were found to be similar between groups when comparing participants taking SJW with those taking pharmaceutical antidepressants, including imipramine together with placebo (1 RCT, n=324), fluoxetine (2 RCTs, n=310) and sertraline (2 RCTs, n=271).
The results demonstrated a drop in the HAM-D scores for participants taking SJW compared with placebo, and were equivalent to taking pharmaceutical antidepressents for the treatment of mild to moderate depression.
Inclusion criteria were clearly defined in terms of the study design, intervention and outcomes. Several relevant sources were searched. Only studies published in English were included, which means other relevant studies might have been missed. Methods were used to minimise error and bias in the assessment of validity and data extraction, but it is not clear whether similar steps were taken at the study selection stage. The narrative synthesis appears appropriate given the clinical diversity among the studies. However, the results for individual studies were reported without levels of statistical significance, which means it is not possible to verify the findings reported in the review. The small sample sizes, variations between studies and lack of reporting of levels of statistical significance mean that the results may not be reliable.
Implications of the review for practice and research
Practice: The authors stated that practitioners may find SJW a viable complementary treatment alternative to traditional pharmaceutical treatment. However, participants taking oral contraception, loperamide and theophylline should be closely monitored as SJW can interfere with these medications. Practitioners should utilise appropriate screening tools and have a knowledge of the effectiveness of complementary treatments as well as pharmaceutical treatments.
Research: The authors stated that further studies are needed to evaluate the effects of SJW; these should be well-conducted, well-reported RCTs adhering to CONSORT guidelines. Future trials should use the German Commission E Monographs, which provide guidelines for standardised manufacturing and development of herbal medicines.
Clement K, Covertson C R, Johnson M J, Dearing K. St. John's Wort and the treatment of mild to moderate depression: a systematic review Holistic Nursing Practice 2006; 20(4): 197-203
Subject indexing assigned by NLM
Antidepressive Agents /therapeutic use; Depression /drug therapy /nursing; Depressive Disorder /drug therapy /nursing; Humans; Hypericum; Nursing Methodology Research; Patient Satisfaction /statistics & numerical data; Phytotherapy /nursing; Plant Extracts /therapeutic use; Randomized Controlled Trials as Topic; Treatment Outcome
Database entry date
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.