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Quantitative patch and repeated open application testing in methyldibromo glutaronitrile‐sensitive patients
Author(s) -
Schnuch A.,
Kelterer D.,
Bauer A.,
Schuster Ch.,
Aberer W.,
Mahler V.,
Katzer K.,
Rakoski J.,
Jappe U.,
Krautheim A.,
Bircher A.,
Koch P.,
Worm M.,
Löffler H.,
Hillen U.,
Frosch P. J.,
Uter W.
Publication year - 2005
Publication title -
contact dermatitis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 96
eISSN - 1600-0536
pISSN - 0105-1873
DOI - 10.1111/j.0105-1873.2005.00529.x
Subject(s) - confidence interval , allergic contact dermatitis , medicine , patch test , contact allergy , patch testing , contact dermatitis , allergy , gastroenterology , immunology
Contact allergy to methyldibromo glutaronitrile (MDBGN), often combined with phenoxyethanol (PE) (e.g., Euxyl K 400 ® ), increased throughout the 1990s in Europe. Consequently, in 2003, the European Commission banned its use in leave‐on products, where its use concentration was considered too high and the non‐sensitizing use concentration as yet unknown. The 2 objectives of the study are (a) to find a maximum non‐eliciting concentration in a leave‐on product in MDBGN/PE‐sensitized patients, which could possibly also be considered safe regarding induction and (b) to find the best patch test concentration for MDBGN. We, therefore, performed a use‐related test (ROAT) in patients sensitized to MDBGN/PE ( n = 39) with 3 concentrations of MDBGN/PE (50, 100 and 250 p.p.m. MDBGN, respectively). A subset of these patients ( n = 24) was later patch‐tested with various concentrations (0.1, 0.2, 0.3 and 0.5% MDBGN, respectively). 15 patients (38%, 95% confidence interval (CI) = 23–55%) had a negative and 24 (62%; 95% CI = 45–77%) a positive overall repeated open application test (ROAT) result. 13 reacted to the lowest (50 p.p.m.), 8 to the middle (100 p.p.m.) and 3 to the highest concentration (250 p.p.m.) only. In those 13 reacting to the lowest ROAT concentration, dermatitis developed within a few days (1–7). The strength of the initial and the confirmatory patch test result, respectively, and the outcome of the ROAT were positively associated. Of the 24 patients with a use and confirmatory patch test, 15 reacted to 0.1% MDBGN, 16 to 0.2%, 17 to 0.3% and 22 to 0.5%. With the patch test concentration of 0.5%, the number of ROAT‐negative patients but patch‐test‐positive patients increases considerably, particularly due to + reactions. A maximum sensitivity of 94% (95% CI = 70–100%) is reached with a patch test concentration of 0.2%, and is not further improved by increasing the concentration. However, the specificity decreases dramatically from 88 (95% CI = 47–100%) with 0.2% to a mere 12.5% (95% CI = 0–53%) with 0.5%. It can be concluded (a) that for MDBGN 0.2% is very likely the best patch test concentration and (b) that 50 p.p.m. in a leave‐on product can elicit contact dermatitis in sensitized persons. We were, therefore, unable to find a safe, still microbicidal, concentration for leave‐on products. By contrast, with other contact allergens, dose–response use tests may be able to identify a non‐eliciting concentration, which could give valuable clues to a non‐inducing (i.e., safe) concentration in products.