Prevalence and trend of allergen sensitization in patients referred for patch testing with a final diagnosis of psoriasis: North American Contact Dermatitis Group data, 2001-2016

Background: Little is known about the relationship between psoriasis and allergic contact dermatitis (ACD). Objective: To examine the associations with ACD, related clinical characteristics, and common positive and clinically relevant allergens of patients with a final diagnosis of psoriasis who were referred for patch testing. Methods: Retrospective analysis of 38 723 patients from the North American Contact Dermatitis Group. Results: Patients with a final diagnosis of psoriasis had lower proportions of ACD than those without psoriasis (32.7% vs 57.8%). In multivariable logistic regression models, psoriasis was inversely associated with female sex, Black or Asian race, and history of atopic dermatitis and hay fever. Patients with a final diagnosis of psoriasis were less likely to have one or more positive allergic patch-test reactions or to have a current clinically relevant patch-test reaction to the majority of the most commonly positive and/or relevant allergens. The most clinically relevant allergens included nickel sulfate, methylisothiazolinone, and fragrance mix I. Conclusion: Approximately one-third of patients who were referred for patch testing with a final diagnosis of psoriasis were also diagnosed with ACD. In select patients with suspected psoriasis who also have a clinical presentation suggestive of ACD, patch testing may be helpful.