Patch test results from the Mayo Clinic Contact Dermatitis Group, 1998-2000.

Background: Patch testing is a diagnostic tool for the evaluation of patients with suspected allergic contact dermatitis. A standard series of allergens similar to that used by the North American Contact Dermatitis Group (NACDG) is used at Mayo Clinic. Objective: Our aim was to report the results of patch testing with a standard series at Mayo Clinic from July 1, 1998, to Dec 31, 2000 and to compare our findings with those of the NACDG during the same period. Methods: The results of patch testing with the standard series at Mayo Clinic were examined. Positive reaction rates were compared between Mayo Clinic and the NACDG. Results: During the 30- month period, 1324 Mayo Clinic patients were patch tested with a standard series of allergens (mean, 60 allergens), whereas the NACDG standard series during this period included 50 allergens. Overall, 917 patients (69.3% ) had at least one positive reaction and 606 patients (45.8% ) had two or more positive reactions. The 10 allergens used both by Mayo Clinic and by the NACDG that most frequently caused positive reactions were nickel sulfate hexahydrate, balsam of Peru (Myroxylon pereirae), neomycin sulfate, cobalt chloride, fragrance mix, potassium dichromate (0.25% ), thimerosal, bacitracin, formaldehyde, and glutaraldehyde. Statistically significant differences in positive reaction rates (P < .05) were observed for 12 of the 43 allergens common to both Mayo Clinic and the NACDG. Conclusion: With large standard patch test series, one can identify commonly encountered and potentially relevant contact allergens.