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Can patch testing with methylchloroisothiazolinone/methylisothiazolinone be optimized using a new diagnostic mix? – A multicenter study from the Swedish Contact Dermatitis Research Group
Author(s) -
Engfeldt Malin,
Isaksson Marléne,
BråredChristensson Johanna,
Hagvall Lina,
Matura Mihály,
Ryberg Kristina,
Stenberg Berndt,
Svedman Cecilia,
Bruze Magnus
Publication year - 2020
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/cod.13483
Subject(s) - contact allergy , patch test , medicine , dermatology , contact dermatitis , allergic contact dermatitis , allergy , immunology
Abstract Background Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and methylisothiazolinone (MI) are tested to detect contact allergy to these isothiazolinones. Objectives To study if an aqueous patch test preparation with MCI and MI in a mix of 0.015% and 0.2%, respectively, detects more contact allergies than the commonly used preparations of MCI/MI in 0.02% aq. and MI in 0.2% aq. Methods A total of 1555 patients with dermatitis in five Swedish dermatology departments were tested consecutively with MCI/MI 0.215% aq., MCI/MI 0.02% aq., and MI 0.2% aq. Results The share of contact allergy to MCI/MI 0.215% aq., MCI/MI 0.02% aq., and MI 0.2% aq. varied in the test centers between 7.9% and 25.9%, 3.2% and 10.3%, and 5.8% and 12.3%, respectively. MCI/MI 0.215% aq. detected significantly more patch‐test positive individuals than both MCI/MI 0.02% aq. ( P < .001) and MI 0.2% aq. ( P < .001), as well as either one of MCI/MI and MI ( P < .001). In the patients only reacting to MCI/MI 0.215% aq., 57.7% were recorded as having a dermatitis that was explained or aggravated by exposure to either MCI/MI or MI. Conclusion The results speak in favor of replacing the preparations MCI/MI 0.02% aq. and MI 0.2% aq. with MCI/MI 0.215% aq. as the screening substance in the Swedish baseline series, which has been implemented in 2020.