Allergy DIAGNOSIS THE ATOPY PATCH TEST—REPRODUCIBILITY AND COMPARISON OF DIFFERENT EVALUATION METHODS

Heinemann C, Schliemann-Willers S, Kelterer D, et al. Allergy. 2002;57:641–645 Purpose of the Study. Atopy patch testing (APT) has been suggested to be a valuable tool in the diagnosis of allergy. The purpose of this study was to examine the reproducibility of APT results and to compare visual evaluation to chromametry and laser Doppler imaging. Study Population. Fifty-two patients with atopic dermatitis. Methods. APT was performed on tape-stripped and unstripped test fields on their backs using cat dander, house dust mite, and grass pollen allergens from 2 different suppliers. Responders were retested 4 to 12 weeks later with the same allergens on their forearms. Results. Fourteen (26.9%) volunteers showed 1 or more positive reactions. The reproducibility rate was 56.3%. The test agreement in volunteers tested with allergens from the 2 different manufacturers was poor. Correlation of the results between the three evaluation methods was significant (P .001). Compared with chromametry and laser Doppler imaging, visual scoring was superior in differentiation between irritative and allergic reactions. Conclusions. The low reproducibility rate of APT results and the poor inter-test-agreement using allergens from different suppliers show that much work remains to make APT a reliable tool in identifying relevant aeroallergens in patients with atopic dermatitis. Reviewer’s Comments. APT has been proposed as a useful adjunct for the diagnosis of allergy, especially in patients with atopic dermatitis and allergic gastrointestinal disease. If perfected, the test could be of particular value for non–immunoglobulin E (IgE)-mediated conditions where skin testing and radioallergosorbent testing (RAST) will not be useful. However, as demonstrated in this study, there is still a great deal of work to be done before this test can be reliably applied to clinical practice.