Information on Additional Echinacea Trials

To the Editor:

It is great to see that the authors of the recently published review of Echinacea¹ were using an evidence-based approach to the literature. They gave a thorough description of the selection criteria, methods of data collection, and analysis of the literature. However, the following 2 points should be mentioned.

The authors state that there have been no trials conducted using infants and children, and therefore, Echinacea should be used with caution in those populations. A review published in Phytomedicine² in 1996 mentions 5 trials^3-7 in infants and children, and a sixth trial was found through a search in the Micromedex Complementary and Alternative Medicine Series.⁸ None of these demonstrated any adverse events. The review article concluded that Echinacea is safe for a wide range of ages, infants to adults.²

Despite the numerous Echinacea articles reviewed, the authors also did not include a randomized placebo-controlled trial by Dorn and colleagues⁹ in Complementary Therapies in Medicine. This trial has been referenced in several studies, and a review was published in HerbalGram in July 1998. Dorn and coworkers conducted a placebo-controlled double-blinded trial assessing the use of Echinacea pallidae for the treatment of upper respiratory tract infections. One hundred sixty patients were randomized to placebo or active treatment. Outcomes measured included the duration of the illness, reduction of symptoms, and change in lymphocyte and segmented neutrophil counts in patients with either viral or bacterial infections. Results showed a statistically significant reduction in duration of illness for both bacterial and viral infections (P <.001). Clinical findings showed that lymphocyte and neutrophil counts returned to normal faster in the treatment group than in the placebo group.

Since Barrett and colleagues went to great lengths to obtain articles, including those in German, it is surprising that the Dorn trial and the 6 pediatric trials were not included. Although inclusion of this additional information would not have changed the recommendation regarding Echinacea’s efficacy, it would have affected the recommendation for infants and children and provided even more evidence of the safety and efficacy of Echinacea in patients of all ages.

Ginger Ertel, PharmD candidate
Harold Manley, PharmD
Cydney McQueen, PharmD
Patrick Bryant, PharmD
University of Missouri
Kansas City
E-mail: gertel@email.msn.com

REFERENCES

1. Barrett B, Vohmann M, Calabrese C. Echinacea for upper respiratory infection. J Fam Pract 1999; 48:628-35.
2. Parnham MJ. Benefit-risk assessment of the squeezed sap of the purple coneflower (Echinacea purpurea) for long-term oral immunostimulation. Phytomedicine 1996; 3:95-102.
3. Baetgen D. Pertussistherapie mit Myo-Echinacin in der kinderpraxis. Med Monatschr 1964; 18:129-31.
4. Baetgen D. Erfolge in der keuchhustenbehandlung mit Echinacin. Therapiewoche 1984; 34:5115-9.
5. Heesen W. Unspezifische behandlungsmoglichkeiten bei tuberkulosen erkrankungen. Erfahrungsheilkunde 1964; 13:210-7.
6. Volz G. Zur keuchhustenbehandlung mit Myo-Echinacin. Ther Gegenwart 1957; 96:312-3.
7. Zimmermann O. Die therapie des keuchhusten mit Myo-Echinacin. Hippokrates 1969; 6:223-35.
8. Kohler G. Esberitox: clinical expert report. Salzgitter, Germany: Schaper & Brummer; 1997.
9. Dorn M, Knick E, Lewith G. Placebo-controlled, double-blind study of Echinacea pallidae radix in upper respiratory tract infections. Complem Ther Med 1997; 5:40-4.

The preceding letter was referred to Drs Barrett, Vohmann, and Calabrese, who reply as follows:

We were pleased to see the letter from Ertel and colleagues, which helpfully makes reference to publications not cited in our review article. We would like to reply to their 2 major points. First, to our knowledge none of the trials using children met our inclusion criteria of being randomized, double-blinded, and placebo-controlled. Additionally, we would like to point out that 4 of the pediatric trials were for treatment of pertussis and the fifth for tuberculosis. Our review focussed on trials of Echinacea for acute upper respiratory infection and flulike illness. Second, the trial described in the 1997 article by Dorn and colleagues was previously described by Bräunig and Knick in 1993¹ and was included in our review. We apologize for any confusion caused by not citing the second write-up of this important trial.

We would also like to take this opportunity to mention a second write-up of the trial described by Brinkeborn and coworkers.² This second write-up clarified several issues that were not addressed in the 1998 article³ and generally assessed it as a relatively high-quality trial demonstrating positive results. Nevertheless, we would again like to point out that the evidence of Echinacea’s effectiveness as a treatment for the common cold is moderate at best; the timing and dose of optimal treatment is unknown; the specific type of Echinacea preparation that should be used is unknown; and there have been no appropriate trials in pediatric, obstetric, or elderly populations. Hence, caution should be advised. A great deal more research needs to be done.