Echinacea in the prevention of induced rhinovirus colds: A meta-analysis

Imperial College London, Londinium, England, United Kingdom
Clinical Therapeutics (Impact Factor: 2.59). 02/2006; 28(2):174-83. DOI: 10.1016/j.clinthera.2006.02.001
Source: PubMed

ABSTRACT The therapeutic effectiveness of Echinacea in the treatment and the prevention of colds has been debated. Studies of naturally occurring colds are hampered by variability in time from onset of symptoms to treatment and by heterogeneity in trial design. Experimental infection studies allow for the standardization of time to initiation of treatment, virus type and dose, and immune competence of volunteers.
To determine whether the negative results obtained in previous studies of Echinacea were a consequence of efficacy or of inadequate sample size, we performed a meta-analysis of experimental rhinovirus infection studies on the efficacy of Echinacea extracts to prevent symptomatic development of an experimentally induced cold.
We carried out a systematic search of English- and German-language literature using the MEDLINE, EMBASE, CAplus, BIOSIS, CABA, AGRICOLA, TOXCENTER, SCISEARCH, NAHL, and NAPRALERT, databases and the search terms Echinacea, black Sampson, coneflower, and Roter Sonnenbut. Matching documents were then searched for > or = 1 of the following terms: rhinovirus, RV, inoculation, Inokulation, induced, induziert, artificial, and artifiziell. Suitable studies were identified and pooled for analysis. The primary end point was the development of symptomatic clinical colds, as defined by the authors of the original studies. Results were reported as differences in the proportion of subjects with symptomatic episodes of a common cold, expressed as odds ratios (ORs) and 95% CIs. The secondary outcome was the difference in total symptom severity scores between treatment groups (assessed daily by integrating the severity scores of 8 individual cold-related symptoms that were rated on a scale from 0 [absent] to 4 [very severe]).
A total of 234 articles were identified through the literature search; 231 were excluded from the analysis because they related to studies of spontaneous common colds. Three suitable studies were selected for pooling of data. Based on the analysis, the likelihood of experiencing a clinical cold was 55% higher with placebo than with Echinacea (OR, 1.55 [95% CI, 1.02-2.36]; P<0.043). The absolute difference in total symptom scores between groups was -1.96 (95% CI, -4.83 to 0.90; P=NS).
This meta-analysis suggests that standardized extracts of Echinacea were effective in the prevention of symptoms of the common cold after clinical inoculation, compared with placebo. Further prospective, appropriately powered clinical studies are required to confirm this finding.

    • "Many published works have described both the chemistry and bioactivity in vitro and in vivo of these plants and some of their phytoconstituents (Bauer, 1999; Binns et al., 2002; Barnes et al., 2005; Woelkart et al., 2008). However , contrasting results about Echinacea efficacy (Schoop et al., 2006; Woelkart et al., 2008) have been reported. This is mainly attributable to the fact that the products under study were not comparable because they belonged to different Echinacea species or different commercial/botanical preparations or even different Echinacea components. "
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    • "2007 [46] + + Herbal remedies Ecchinacea, thuja, aronia, aloe, grapefruit concentrates, traditional Tibetan herbs [48] [49] [51] +/À Homeopathy Calcarea carb, Pulsatilla, Sulphur 2005 [53] À Fungal derived remedies Beta-glucan 1999, 2008 [54] [55] À "
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    ABSTRACT: Parents of children suffering from recurrent respiratory infections can be persuaded by advertisements to pressure their family physicians and pediatricians for "immune-stimulating enhancements". However, the evidence base behind these immune stimulants is usually lacking. Often there is no peer-reviewed studies available that support claims made by "immune-booster" supplements. In this review, we critically analyze most of the marketed immuno-active drugs (including vitamin preparations, dietary supplements, homeopathic remedies, Ecchinacea, bacterial lysates, and probiotics) and identify the necessity to exclude an immunodeficiency in every child suffering from recurrent respiratory tract infections.
    Paediatric Respiratory Reviews 10/2013; DOI:10.1016/j.prrv.2013.10.006 · 2.22 Impact Factor
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    • "Three studies on artificially induced rhinovirus infections showed a trend toward preventing symptomatic cold episodes by Echinacea [19– 21]. Generally, the prophylactic benefits reached significance when data were pooled in a meta-analysis, because single studies tended to have small sample sizes and undefined or low statistical power [22]. On the other hand, a good safety profile is mandatory for therapies that are designed to be taken over several months [23]. "
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    ABSTRACT: Objective. To investigate the safety (risk) and efficacy (benefit) of Echinacea purpurea extract in the prevention of common cold episodes in a large population over a 4-month period. Methods. 755 healthy subjects were allocated to receive either an alcohol extract from freshly harvested E. purpurea (95% herba and 5% root) or placebo. Participants were required to record adverse events and to rate cold-related issues in a diary throughout the investigation period. Nasal secretions were sampled at acute colds and screened for viruses. Results. A total of 293 adverse events occurred with Echinacea and 306 with placebo treatment. Nine and 10% of participants experienced adverse events, which were at least possibly related to the study drug (adverse drug reactions). Thus, the safety of Echinacea was noninferior to placebo. Echinacea reduced the total number of cold episodes, cumulated episode days within the group, and pain-killer medicated episodes. Echinacea inhibited virally confirmed colds and especially prevented enveloped virus infections (P < 0.05). Echinacea showed maximal effects on recurrent infections, and preventive effects increased with therapy compliance and adherence to the protocol. Conclusions. Compliant prophylactic intake of E. purpurea over a 4-month period appeared to provide a positive risk to benefit ratio.
    Evidence-based Complementary and Alternative Medicine 09/2012; 2012:841315. DOI:10.1155/2012/841315 · 1.88 Impact Factor
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