engleski

The importance of 7th day patch test readings

Introduction Contact dermatitis is an oftentimes chronic or recurring inflammatory eczematous skin disease induced by contact irritants or allergens. Epicutaneous (patch) test is a golden standard in the diagnosis of contact allergy, performed by placing allergens on the uninvolved skin under an occlusive patch. Patch test readings for identification of an eczematous (positive) reaction are usually performed on Day 2 and Day 3-5. Additional readings on Day 7 are also becoming a standard but are not regularly employed due to practical reasons. Aim of our study was to assess the value of a 7th day reading in evaluating late positive reaction on a patch test and to identify allergen groups associated with new positive Day7 reactions. Materials and methods Patients included in this study underwent patch testing with a standard series of 31 allergens. Data were collected through the hospital information system while maintaining the privacy and confidentiality of the respondents. Results were processed retrospectively for the period from May 2018 to June 2020. All patients referred for patch testing from May 2018 to June 2020 in whom the same was performed, became the subjects of this study. The patch test was performed by applying the allergen with test patches to the upper back ; on healthy, untreated skin. The skin reaction was studied after 2, 3 and 7 days. Results Out of 345 tests performed, 44 allergens induced positive reaction for the first time on the seventh day. Most often it was nickel sulfate, neomycin sulfate and thimerosal. This means that without the additional reading we would miss 13% positive tests. Discussion Our results confirm the importance of implementing patch test reading on the seventh day for detecting late positive reactions. Therefore, Day 7 readings should become a part of a complete diagnostic evaluation of contact allergies on the standard series of allergens.

contact allergy ; nickel allergy ; patch test

nije evidentirano