Is electrodermal testing as effective as skin prick tests for diagnosing allergies? A double blind, randomised block design study

Studies of electrodermal testing

Several studies have considered electrodermal testing as a means of evaluating "allergy" but these have been scientifically inadequate.[1][2][3][4][5][6] Tsuei et al[1] compared the use of the Dermatron with RAST and provocative intradermal skin testing for food intolerance and reported that electrodermal testing showed the best correlation with blind diagnostic food challenge. Fuller Royal et al and Fox stated that this method is rapid, "accurate," and as "effective" as any other for defining food intolerance, but again these conclusions are based on unblinded and descriptive studies.[2] [3] A double blind study comparing the results of IgE antibody levels for a variety of pollens and moulds with electrodermal testing for the same allergens in 20 patients demonstrated a 73% correlation between the two methods of testing.[4] Krop et al compared provocative intradermal testing with the Vegatest in order to identify sensitivities to foods, chemicals, and inhalants and found a significant correlation between the two[5]; however, comparing two unconventional techniques for diagnosing allergy is fraught with difficulties.

A further study by Krop et al evaluated electrodermal testing in two groups of patients using double blind methodology designed to test whether electrodermal testing could differentiate between histamine and house dust mite and water and saline in patients who had a positive result to a skin prick test for house dust mite.[6] Initially, 41 patients were electrodermally tested; and "blind" testers using identical, coded test ampoules were able to discriminate between allergen and non-allergen in 82% of the cases. A subsequent study of 24 patients, using the same double blind, randomised methodology, showed that blind testers could discriminate 96% of the time between allergic and non-allergic substances.[6] Katelaris has published a critical report on the use of the Vegatest for diagnosing food intolerance and concludes that the Vegatest is a pseudoscientific clinical tool that is of no diagnostic value.[7] In the case of IgE dependent allergic responses, there is a clearly understood mechanism whereby mast cells and basophils release proinflammatory mediators in response to allergen exposure.[8] It is difficult to connect this known pathophysiological mechanism with any theory that embraces a change in whole body electrical conductivity.

1. Tsuei J and Madill P. A food allergy study using the EAV acupuncture technique. Am J Acupunct 1984;12:105-16.
2. Fuller Royal F, Fuller Royal D. Scientific support for electrodiagnosis. Br Homoeopathic J 1991;18:166-78.
3. Fox A. Determination of neutralisation point for allergic hypersensitivity. Br Homoeopathic J 1987;76:230-4.
4. Ali M. Correlation of IgE antibodies with specificity for pollen and mould allergy changes in electrodermal skin responses following exposure to allergens. Am J Clin Pathol 1989;91:357-9.
5. Krop J, Swiesczek J, Wood A. Comparison of ecological testing with the Vegatest method in identifying sensitivities to chemicals, foods and inhalants. Am J Acupunct 1985;13:253-9.
6. Krop J, Lewith, G, Gziut W, Radulescu C. A double-blind, randomised, controlled investigation of electrodermal testing in the diagnosis of allergies. J Altern Complement Med 1997;3:241-8.
7. Katelaris CH. Vegatesting the diagnosis of allergic conditions. Med J Aust 1991;155:113-4.
8. Holgate ST, Robinson C, Church MK. Mediators of immediate hypersensitivity. In: Middleton E, Reed CE, Ellis EF, eds. Allergy, principles and practice. Vol 1. St Louis: Mosby, 1993: 267-301.