Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD).
This study documents the North American Contact Dermatitis Group (NACDG) patch-testing results from January 1, 2011, to December 31, 2012.
At 12 centers in North America, patients were tested in a standardized manner with a series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends analyzed using χ2 statistics.
Four thousand two hundred thirty-eight patients were tested; of these, 2705 patients (63.8%) had at least 1 positive reaction, and 2029 (48.0%) were ultimately determined to have a primary diagnosis of ACD. Four hundred eight patients (9.6%) had occupationally related skin disease. There were 7532 positive allergic reactions. As compared with previous reporting periods (2009–2010 and 2000–2010), positive reaction rates statistically increased for 6 allergens: methylchloroisothiazolinone/methylisothiazolinone (5.0%; risk ratios [RRs]: 2.01 [1.60–2.52], 1.87 [1.61–2.18]), lanolin alcohol (4.6%; RRs 1.83 [1.45–2.30], 2.10 [1.79–2.47]), cinnamic aldehyde (3.9%; 1.69 [1.32–2.15], 1.53 [1.28–1.82]), glutaral (1.5%; 1.67 [1.13–2.48], 1.31 [1.00–1.71]), paraben mix (1.4%; 1.77 [1.16–2.69], 1.44 [1.09–1.92]), and fragrance mix I (12.1%; RRs 1.42 [1.25–1.61], 1.24 [1.14–1.36]). Compared with the previous decade, positivity rates for all formaldehyde-releasing preservatives significantly decreased (formaldehyde 6.6%; RR, 0.82 [0.73, 0.93]; quaternium-15 6.4% RR 0.75 [0.66, 0.85]; diazolidinyl urea 2.1%; RR, 0.67 [0.54, 0.84]; imidazolidinyl urea 1.6%, 0.60 [0.47, 0.77]; bronopol 1.6%; RR, 0.60 [0.46, 0.77]; DMDM hydantoin 1.6%; RR, 0.59 [0.54, 0.84]). Approximately a quarter of patients had at least 1 relevant allergic reaction to a non-NACDG allergen. In addition, approximately one-fourth to one-third of reactions detected by NACDG allergens would have been hypothetically missed by T.R.U.E. TEST (SmartPractice Denmark, Hillerød, Denmark).
These data document the beginning of the epidemic of sensitivity to methylisothiazolinones in North America, which has been well documented in Europe. Patch testing with allergens beyond a standard screening tray is necessary for complete evaluation of occupational and nonoccupational ACD.
From the University of Minnesota and the Minneapolis VAMC; University of California, San Francisco; Cleveland Clinic, Ohio; McGill University Health Centre, Montreal; University of Toronto, Canada; Ohio State University, Columbus; Associates in Dermatology, Fort Myers, Fla; Group Health Associates, Cincinnati, Ohio; Dartmouth Medical Center, Lebanon, NH; St. Luke’s Roosevelt Hospital Center, New York, NY; Dermatology Specialists, Louisville, KY; Pennsylvania State University Hershey; University of Ottawa, Canada; Oregon Health Sciences University, Portland; and Columbia University Medical Center, New York, NY.
Address correspondence to Erin M. Warshaw, MD, MS, Dept 111 K VAMC, Dermatology, 1 Veterans Dr, Minneapolis, MN 55417. E-mail: firstname.lastname@example.org.
This material is the result of work supported with resources and the use of facilities at the Minneapolis Veterans Affairs Health Care System.
The authors have no funding or conflicts to declare.
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.