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

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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.


Enheter & grupper
Externa organisationer
  • Skåne University Hospital
  • Göteborgs universitet
  • Skaraborg Hospital
  • Karolinska Institute
  • NU Hospital Group
  • Umeå University

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Dermatologi och venereologi


TidskriftContact Dermatitis
StatusE-pub ahead of print - 2020 feb 28
Peer review utfördJa