For patients with allergic skin and respiratory diseases, an atopy patch test with aeroallergens could be a beneficial clinical tool to help increase correct diagnosis of allergens, according to study data published in the Journal of the European Academy of Dermatology and Venereology.
The aim of this retrospective, multicenter study was to compare the reaction frequency and diagnostic significance of standard patch testing with biologically standardized aeroallergen patch testing in patients with suspected contact dermatitis with aeroallergen involvement. Data were collected from databases associated with the Information Network of Departments of Dermatology clinics and included information regarding patients’ history, clinical records, and patch test results. Patch test results were based on the International Contact Dermatitis Research Group scoring system, and reaction profiles were coded as irritant, follicular, doubtful, weak, and strong positive reactions.
Of the 3676 patients included in the study group, 34.8% were men, the median age was 41 years, and 54.5% had atopic dermatitis. The cohort of patients tested with the aeroallergens were more frequently younger women who had a history of atopic dermatitis. The most frequent patch test reactions were to Dermatophagoides pteronyssinus (19.6%), Dermatophagoides farinae (16.9%), birch (6.2%), timothy grass (6.0%), cat dander (5.4%), mugwort (4.9%), and dog dander (4.6%). Less common reactions were found to 5 grasses (3.2%), cocksfoot (2.1%), and plantain (1.6%). Overall, patients with atopic dermatitis had more positive reactions, and house dust mites were the most frequent aeroallergen that caused a positive reaction. Allergic rhinitis increased the chance of a positive aeroallergen test reaction but allergic asthma did not.
Limitations of this study included the potential of unreliable clinical relevance, not having records for the results of skin prick or IgE testing for comparison with patch test results, and not using the revised European Task Force on Atopic Dermatitis recommendations, which includes different categories for positive patch test reactions.
The researchers concluded that the “atopy patch test with aeroallergens is a useful [clinical] tool for assessing cutaneous delayed-type reactions to protein allergens in patients with allergic skin diseases and respiratory diseases.” They added that for patients with respiratory disorders, “the atopy patch test may complement the routine diagnostic workup of a suspected allergy to aeroallergens by means of a skin prick test and/or IgE test. Finally, positive aeroallergen patch tests are not limited to AD patients, as the originally proposed name ‘atopy patch test’ suggests.”
Dickel H, Kuhlmann L, Bauer A, et al. Atopy patch testing with aeroallergens in a large clinical population of dermatitis patients in Germany and Switzerland, 2000-2015: a retrospective multicentre study [published online January 30, 2020]. J Eur Acad Dermatol Venereol. doi: 10.1111/jdv.16250