Patch Test Results With Additions to the European Baseline Series, 2021/22-Joint European Results of the ESSCA<SUP>A</SUP> and the EBS<SUP>B</SUP> Working Groups of the ESCD, and the GEIDAC©

Abstract

Background: Allergens are periodically added to the European Baseline Series (EBS) to audit their value in consecutive patch testing. Objectives: To present results of audit allergens tested in consecutive patients in 54 departments in 13 European countries during 2021 and 2022. Methods: Anonymized or pseudonymized individual data, and partly aggregated data on patch test rest results and their clinical relevance were prospectively collected and centrally pooled and analyzed. Results: In 2021 and 2022, 18 832 patients were patch tested with the EBS, and 2860 with the TRUE Test baseline series (supplemented with some missing EBS allergens). Of these patients, 17 359 were additionally tested with one or more of the 19 audit allergen preparations examined. Apart from the terpene hydroperoxides (OOH) which yielded the highest numbers of positive patch test reactions (linalool-OOH 1% pet.: 7.65 (7.09%-8.23%) [95% CI] and limonene-OOH 0.3% pet. 6.78 (6.26%-7.32%)), positive reactions were most often seen to benzisothiazolinone (3.71 (3.3%-4.15%)), sodium metabisulfite (3.49 (3.14%-3.88%)), Evernia furfuracea (tree moss, 1.79 (1.4%-2.26%)), and decyl and lauryl glucoside, at 1.49 (1.25%-1.76%) and 1.26 (1.05%-1.51%), respectively. The other allergens yielded around 1% or fewer positive patch test reactions. Clinical relevance varied, with Evernia furfuracea, 2-bromo-2-nitropropane-1,3-diol and terpene hydroperoxides considered relevant in more than 2/3 cases, while for other frequent sensitizers benzisothiazolinone and sodium metabisulfite, relevance could be confirmed in half of the cases or less often. Conclusions: The current results, along with other published data, will serve to inform decisions concerning possible revision of the EBS, considering frequency of positive reactions, their clinical relevance and the overall reaction profile of each of the allergens.