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North American Contact Dermatitis Group Patch Test Results: 2021-2022
Marie-Claude Houle1, Joel G DeKoven2, Amber Reck Atwater3
1From the Division of Dermatology, Centre Hospitalier Universitaire Québec, Laval University, Québec, Canada.
Dermatitis : Contact, Atopic, Occupational, Drug
|April 24, 2025
Summary
Patch testing for allergic contact dermatitis (ACD) revealed increasing nickel and cobalt allergies, while methylisothiazolinone (MI) allergy prevalence declined. Many patients reacted to allergens not in the standard screening series.
Area of Science:
- Dermatology
- Allergology
- Epidemiology
Background:
- Patch testing is crucial for diagnosing allergic contact dermatitis (ACD).
- The North American Contact Dermatitis Group (NACDG) collects data on patch testing results.
- Understanding current allergen prevalence is vital for clinical practice and public health.
Purpose of the Study:
- To report NACDG patch testing results from 2021-2022.
- To identify common allergens and trends in ACD.
- To assess the prevalence of reactions to allergens outside the standard screening series.
Main Methods:
- Standardized patch testing with an 80-allergen screening series was performed at 12 North American centers.
- Data from 3056 patients tested between 2021 and 2022 were analyzed.
- Statistical comparisons were made with previous NACDG data (2019-2020).
Main Results:
- 72.0% of patients had at least one positive patch test reaction; 46.6% were diagnosed with ACD.
- Most common allergens: nickel sulfate (24.9%), MI (11.5%), hydroperoxides of linalool (10.1%), cobalt chloride (9.2%).
- Statistically significant increases in prevalence were observed for nickel, cobalt, gold, hydroperoxides of limonene, and others compared to 2019-2020. MI positivity continued to decrease.
- 21.1% of patients reacted to allergens not included in the standard screening series.
Conclusions:
- The prevalence of methylisothiazolinone (MI) contact allergy in North America is decreasing.
- Fragrance allergies remain common, but the specific allergens involved are shifting.
- Comprehensive patch testing, including supplemental allergens, is essential for evaluating ACD effectively.
