Rapid Response

Echinacea Use and the Need for More Studies

Authors: Jamal Islam, MD, Susan C. Weller, PhD

Abstract

The use of echinacea in the general population is common despite the continued debate on its efficacy in the scientific community. A previously published meta-analysis by Melchart et al1 and a new analysis by Shah et al2 seek to clarify the controversy on the benefits of echinacea in treating and preventing the common cold. Both analyses focus on randomized placebo-controlled trials; however, Shah et al2 includes an analysis on the prevention as well as duration of colds. In Shah et al,2 14 studies were selected out of 738 studies that were reviewed. Nine of the 14 studies contained information on the incidence of colds. Aggregate results from these nine studies showed a reduced incidence of colds in the echinacea-treated group (OR = 0.42, 95%, CI = 0.25–0.71). However, the effect size (odds ratio) was not consistent across the studies (heterogeneity test, Q statistic P < 0.001).

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References

1. Melchart D, Linde K, Fishcer P, Kaesmayr J. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2000;2.
 
2. Shah S, Sander S, White C, et al. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis 2007;7:473–480.
 
3. Horowitz R. Large scale randomized evidence, large simple trials and overviews of trials: discussion-a clinician’s perspective on meta-analysis. J Clin Epidemiol 1995;48:41–44.
 
4. Chalmers T. Problems induced by meta-analysis. Stat Med 1991;10:971–980.
 
5. Thompson S. Why sources of heterogeneity in meta-analysis should be investigated. BMJ 1994;309:1351–1355.