More comprehensive patch testing could benefit allergic contact dermatitis patients

Patients with allergic contact dermatitis benefited from comprehensive patch testing that included supplemental allergens and substances such as work and personal materials, according to a study.

“Epicutaneous patch testing is an important tool for investigating allergic contact dermatitis (ACD),” Erin M. Warshaw, MD, of the Park Nicollet Contact Dermatitis Clinic and the department of dermatology at the University of Minnesota, both in Minneapolis, and colleagues wrote. “Screening series generally include common sensitizers and are not meant to be comprehensive.”

A retrospective cross-sectional analysis was conducted of North American Contact Dermatitis Group (NACDG) data from a 17-year period.

Researchers evaluated 43,417 dermatitis patients who underwent standardized patch testing with 65 to 70 allergens and supplemental allergens. Of those tested, 9,507 (21.9%) had a reaction to one or more supplemental allergens or substances. Of those, 2,447 (25.7%) had no relevant reactions to the standard allergens in the NACDG screening. In the 65-allergen series, which were completed between 2001 and 2018, a mean of 27.8% of those who had tested positive to supplemental allergens did not have a reaction to the standard test. For the 70-allergen screening, which was conducted between 2009 and 2018, 24.5% of those who had reactions to supplemental allergens did not have a reaction to the standardized allergens.

Positive reaction to one or more allergens, including screening and supplemental allergens, was detected in 30,313 subjects, of which 20,806 (68.6%) had positive reactions only to NACDG standard allergens.

Reactions to only supplemental allergens were detected in 2,447 (8.1%) patients and positive reactions to both were recorded in 7,060 (23.3%) of patients.

“These findings highlight the limitations of testing in a screening series alone,” the authors wrote. “Based on exposure and occupational history, comprehensive patch testing includes testing not only supplemental allergens but also PCPs and workplace materials.”

Therefore, those with contact allergy dermatitis could benefit from more comprehensive patch testing for diagnosis and management.