CRD summary

This review aimed to identify the current body of literature describing the effects of Echinacea on upper respiratory infection symptom severity and quality of life. The authors concluded that the findings of the studies are contradictory about whether Echinacea is beneficial. The review has a number of limitations and the authors' conclusions may not be reliable.

Authors' objectives

To identify the current body of literature describing the effects of Echinacea on upper respiratory infection (URI) symptom severity and quality of life.

Searching

MEDLINE, EMBASE, CINAHL, the Natural Medicines Comprehensive Database and the Cochrane CENTRAL Register were searched from inception to July 2005 for papers in the English language; the search terms were provided. Reference lists were also screened.

Study selection

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction.

Methods of synthesis

Results of the review

Nine double-blind randomised controlled trials (n=2,012) were included.

The findings were mixed. Four of the studies showed statistically significant benefits of Echinacea over placebo, while the remaining studies reported no statistically significant differences. Data on effect sizes and confidence intervals were not reported.

Authors' conclusions

Studies are contradictory about the effect of Echinacea on URI symptom severity and quality of life. Although there were some positive effects, it would be inappropriate to attribute any quality of life benefit to Echinacea given the current data available. However, the possibility cannot be ruled out that Echinacea has a beneficial impact on quality of life.

CRD commentary

The review question was clearly stated, except in terms of the participants and study design. Several relevant databases were searched, though non-English language studies were excluded and no attempts to identify unpublished studies were made; relevant studies may therefore have been missed. It was unclear whether appropriate methods, such as duplicate study selection, were used to minimise error and bias in the review process. Study quality was not assessed and the data reported on participant outcomes were fairly limited. Although there was some discussion of differences between the studies, the authors did not generally go beyond reporting the results of the individual studies. Given the methodological weaknesses of this review, the authors' conclusions may not be reliable.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that further research into Echinacea is required.

Bibliographic details

Gillespie E L, Coleman C I. The effect of Echinacea on upper respiratory infection symptom severity and quality of life. Connecticut Medicine 2006; 70(2): 93-97. [PubMed: 16768061]

Indexing Status

Subject indexing assigned by NLM

MeSH

Echinacea; Humans; Phytotherapy; Plant Extracts /therapeutic use; Quality of Life; Respiratory System /drug effects; Respiratory Tract Infections /drug therapy /physiopathology

AccessionNumber

12006001145

Database entry date

31/01/2007

Record Status

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.