NORTH-AMERICAN CONTACT-DERMATITIS GROUP PATCH TEST-RESULTS FOR THE DETECTION OF DELAYED-TYPE HYPERSENSITIVITY TO TOPICAL ALLERGENS

Background: Allergic contact dermatitis is a significant cause of cuta neous disease affecting many individuals. Patch testing, when used pro perly, often provides support for the diagnosis of allergic contact de rmatitis. Objective: This article reports patch testing results from J uly 1, 1994, to June 30, 1996, by the North American Contact Dermatiti s Group (NACDG). Methods: Patients evaluated in our patch test clinics were tested with the same screening series of allergens by the use of a standardized patch testing technique. The data from these patients were recorded on a standard computer entry form and analyzed. Results: Forty-nine allergens were tested on 3120 patients. Budesonide was add ed to the series in July 1995 and tested on 1678 patients. Of these pa tients, 66.5% had positive allergic patch test reactions, and 57% bad at least one allergic reaction that was felt to be clinically relevant to the present or past dermatitis. The 20 screening allergens commerc ially available to United States dermatologists in the Allergen Patch Test Kit, accounted for only 54.1% of the patients with positive aller gic reactions. The additional 30 allergens on the NACDG screening seri es accounted for 47% of patients with positive allergic reactions. Had the Allergen Patch Test Kit alone been used, 12.4% of all patients te sted may have had their disease misclassified as a nonallergic disorde r, and an additional 34.4% of all tested patients would not have had t heir allergies fully defined. Among those patients with positive respo nses to the supplemental allergens, 81% of the responses were of prese nt or past relevance. The 12 most frequent contact allergens were nick el sulfate, fragrance mix, thimerosal, quaternium-15, neomycin sulfate , formaldehyde, bacitracin, thiuram mix, balsam of Peru, cobalt chlori de, para-phenylenediamine, and carba mix. The present relevance varied with the specific allergen from 10.7% (thimerosal) to 85.7% (quaterni um-15). Among newer allergens, methyldibromoglutaronitrile/phenoxyetha nol (cosmetic preservative) caused positive allergic reactions in 2% o f the patients; tixocortol-21-pivalate and budesonide (corticosteroids ), in 2.0% and 1.1% of the patients, respectively; and ethylene urea/m elamine formaldehyde mix (textile resin), in 5% of the patients. Concl usion: The usefulness of patch testing is enhanced with the number of allergens tested, because allergens not found on the commercially avai lable screening series in the United States frequently give relevant a llergic reactions.