Can patch testing with methylchloroisothiazolinone/methylisothiazolinone be optimized using a new diagnostic mix? - A multicenter study from the Swedish Contact Dermatitis Research Group.

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.

• Authors: Malin Engfeldt, Marléne Isaksson, Johanna Bråred-Christensson, Lina Hagvall, Mihály Matura, Kristina Ryberg, Berndt Stenberg, Cecilia Svedman, Magnus Bruze
• Journal: Contact dermatitis (Contact Dermatitis) Vol. 82 Issue 5 Pg. 283-289 (May 2020) ISSN: 1600-0536 [Electronic] England
• PMID: 32112437 (Publication Type: Journal Article, Multicenter Study)
• Copyright: © 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Chemical References

• Thiazoles
• 2-methyl-4-isothiazolin-3-one
• 5-chloro-2-methyl-4-isothiazolin-3-one

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Child
• Dermatitis, Allergic Contact (diagnosis)
• Female
• Humans
• Male
• Middle Aged
• Patch Tests (methods)
• Sweden
• Thiazoles