Systematic Identification of Copositivity Groups in Standard Series Patch Testing Through Hierarchical Clustering

Area of Science:

• Dermatology
• Allergology
• Immunology

Background:

• Patients often exhibit simultaneous positive reactions to multiple allergens.
• Identifying allergen copositivity groups is crucial for effective contact avoidance strategies.

Purpose of the Study:

• To systematically determine allergen copositivity groups within the Mayo Clinic Standard Series using patient data.
• To identify both known and novel allergen associations.

Main Methods:

• Retrospective cross-sectional analysis of the Mayo Clinic patch test database (2012-2021).
• Analysis of pairwise copositivity rates for 80 allergens in 5943 patients.
• Application of unsupervised hierarchical clustering after background correction.

Main Results:

• Hierarchical clustering revealed distinct allergen copositivity groups.
• Confirmed known associations (e.g., formaldehyde releasers, cobalt-nickel-potassium dichromate).
• Identified novel associations, including glutaraldehyde-sorbitan sesquioleate and benzalkonium chloride-neomycin-bacitracin.

Conclusions:

• Allergen copositivity rates vary, with highly positive allergens showing nonspecific associations.
• Background correction and hierarchical clustering effectively identified known and novel allergen groups.
• Findings aid in guiding contact avoidance for patients with multiple allergen sensitivities.