North American Contact Dermatitis Group Patch Test Results

TLDR

Patch testing is a key diagnostic tool for allergic contact dermatitis, and this study reports standardized results from 12 North American centers using a 70‑allergen screening series during 2009–2010. Data from 4,308 patients were manually verified, entered into a central database, and analyzed with descriptive frequencies and χ² statistics. Positive reactions occurred in 60.7% of patients (46.3% diagnosed with allergic contact dermatitis), with 9.9% occupational disease, 6,855 reactions overall, and shifts in allergen positivity compared to 2007–2008, confirming the value of extensive patch testing.

Abstract

Patch testing is an important diagnostic tool for determination of substances responsible for allergic contact dermatitis.This study reports the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2009, to December 31, 2010.At 12 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 statistics.A total of 4308 patients were tested. Of these, 2614 (60.7%) had at least 1 positive reaction, and 2284 (46.3%) were ultimately determined to have a primary diagnosis of allergic contact dermatitis. Four hundred twenty-seven (9.9%) patients had occupationally related skin disease. There were 6855 positive allergic reactions. As compared with the previous reporting period (2007-2008), the positive reaction rates statistically decreased for 20 allergens (nickel, neomycin, Myroxylon pereirae, cobalt, formaldehyde, quaternium 15, methydibromoglutaronitrile/phenoxyethanol, methylchlorisothiazolinone/methylisothiazolinone, potassium dichromate, diazolidinyl urea, propolis, dimethylol dimethylhydantoin, 2-bromo-2-nitro-1,3-propanediol, methyl methacrylate, ethyl acrylate, glyceryl thioglycolate, dibucaine, amidoamine, clobetasol, and dimethyloldihydroxyethyleneurea; P < 0.05) and statistically increased for 4 allergens (fragrance mix II, iodopropynyl butylcarbamate, propylene glycol, and benzocaine; P < 0.05). Approximately one quarter of tested patients had at least 1 relevant allergic reaction to a non-NACDG allergen. Hypothetically, approximately one quarter of reactions detected by NACDG allergens would have been missed by TRUE TEST (SmartPractice Denmark, Hillerød, Denmark).These results affirm the value of patch testing with many allergens.