Patch testing is an important diagnostic tool for the assessment of allergic contact dermatitis (ACD).
This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2015, to February 28, 2017.
At 13 centers in North America, patients were tested in a standardized manner with a screening series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends were analyzed using χ2 test.
A total of 5597 patients were tested. There were 3725 patients (66.6%) who had at least 1 positive reaction, and 2798 patients (50.2%) were ultimately determined to have a primary diagnosis of ACD. A total of 572 patients (10.2%) had occupationally related skin disease. There were 10,983 positive allergic reactions. Nickel remained the most commonly detected allergen (17.5%). Methylisothiazolinone, which was added to the screening series for the 2013–2014 cycle, had the second highest positive reaction rate of allergens tested (13.4%). Compared with the previous reporting periods (2013–2014) and (2005–2014), positive reaction rates for the top 35 screening allergens statistically increased for only 1 allergen: hydroxyethyl methacrylate (3.4%; risk ratios, 1.24 [confidence interval, 1.00–1.54] and 1.46 [confidence interval, 1.23–1.73]). Three newly added allergen preparations—ammonium persulfate (1.7%), chlorhexidine (0.8%), and hydroquinone (0.3%)—all had a reaction rate of less than 2%. Twenty-three percent of the tested patients had at least 1 relevant allergic reaction to an allergen not on the NACDG series; 12% of these were occupationally related. T.R.U.E. Test (SmartPractice Denmark, Hillerød, Denmark) would have hypothetically missed one quarter to almost 40% of reactions detected by the NACDG screening series.
These results confirm that the epidemic of sensitivity to methylisothiazolinone has continued in North America. Patch testing with allergens beyond a screening tray is necessary for a complete evaluation of occupational and nonoccupational ACD.
From the *Division of Dermatology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada;
†Department of Dermatology, Minneapolis Veterans Affairs Medical Center;
‡Department of Dermatology, University of Minnesota, Minneapolis, MN;
§Dartmouth-Hitchcock Medical Center, Lebanon, NH;
∥Department of Dermatology, University of California San Francisco, San Francisco, CA;
¶Department of Dermatology, Columbia University, New York, NY;
#Division of Dermatology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada;
**Department of Dermatology, Cleveland Clinic, Cleveland, OH;
††University of Louisville, Louisville, KY;
‡‡Department of Dermatology, University of Cincinnati, Cincinnati, OH;
§§Department of Dermatology, Pennsylvania State University, State College, PA;
∥∥Division of Dermatology, University of Ottawa, Ottawa, Ontario, Canada;
¶¶Ohio State University, Columbus, OH; and
##Department of Dermatology, Keck School of Medicine, Los Angeles, CA.
Address reprint requests to Joel G. DeKoven, MD, MHSc, M1-736, 2075 Bayview Ave, Toronto, Ontario, Canada M4N 3M5. E-mail: firstname.lastname@example.org.
This material, in part, is the result of work supported with resources and the use of facilities at the Minneapolis Veterans Affairs Health Care System.
The views expressed in this article are those of the authors and do not necessarily represent the position or policy of the Department of Veterans Affairs or the US Government.
Dr. J.S.T. is a consultant for Johnson & Johnson, Monsanto, Equinox Group, and Kao Brands; is a stockholder for Johnson & Johnson, Express Scripts, Opko Health, Allergan, Astra Zeneca, and Merck; is an author for Decision Support in Medicine; and has a nondependent child who is employed by Pfizer. Dr. M.J.Z. is part owner of AsepticMD; is a speaker, consultant, and investigator for Regeneron/Sanofi; is a speaker for Genentech/Novartis; is a consultant for Fit Bit, L’Oreal, and Menlo; and is an investigator for Leo, Janssen, Incyte, Foamix, DS Biopharma, and UCB. Drs. J.G.D., E.M.W., K.A.Z., H.I.M., D.V.B., D.S., J.F.F.Jr, C.G.T.M., J.G.M., M.D.P., and V.A.D., have no conflicts of interest to disclose.