North American Contact Dermatitis Group Patch Test Results: 2023-2024.

BACKGROUND

Patch testing is the most important diagnostic test for allergic contact dermatitis.

OBJECTIVE

Summarize patch test results from the North American Contact Dermatitis Group (NACDG) of patients tested to a screening series of 80 allergens from 2023 to 2024.

METHODS

Cross-sectional, retrospective analysis.

RESULTS

During the study period, NACDG members tested 3979 patients, and 70.3% had at least one positive/allergic patch test reaction. Tested patients were female (74.3%) and/or White (69.9%); median age was 45 (1 to >89). The most common primary sites of dermatitis were hand (18.9%), face (17.7%), scattered generalized (16.6%), and eyelids (12.8%). Top allergens were nickel sulfate hexahydrate 5% (26.4%), methylisothiazolinone (9.2%), cobalt chloride hexahydrate (8.8%), fragrance mix I (8.7%), hydroperoxides of linalool 1.0% (8.7%), Myroxylon pereirae resin (7.6%), and methylchloroisothiazolinone/methylisothiazolinone (7.0%). Compared to the 2021-2022 cycle, allergy to decyl and coco glucosides and Amerchol L101 increased in positivity, while methylisothiazolinone and methylchloroisothiazolinone/methylisothiazolinone decreased. Over one-fifth (20.1%) of tested patients were positive to a supplemental allergen not on the 80-allergen screening series.

CONCLUSIONS

Allergy to isothiazolinone preservatives decreased in North America while positivity to alkyl glucoside surfactants and Amerchol L101 increased. Comprehensive patch testing with both screening and supplemental series is necessary for the diagnosis and treatment of allergic contact dermatitis.