Patch Test Results With the European Baseline Series, 2021/2022-Joint European Results of the ESSCAA and the EBSB Working Groups of the ESCD, and the GEIDACC.

Background: Patch test results obtained with the European Baseline Series (EBS) in its current version serve both contact allergy surveillance and (re-)assessing the diagnostic value of EBS allergens. Objectives: To present results of current EBS patch testing, obtained in 59 departments in 14 European countries during 2021 and 2022. Methods: Anonymised or pseudonymised individual data, and partly aggregated results, on demographic/clinical characteristics and patch test results with the EBS were prospectively collected, centrally pooled, and retrospectively analysed. Results: In 2021 and 2022, 18 832 patients were patch tested with the EBS. Sensitization to nickel remained most common (18.85 (18.29–19.43)% positivity (95% confidence interval)). Fragrance mix I and Myroxylon pereirae resin yielded very similar results with 6.39 (6.04–6.76)% and 6.5 (6.15–6.87)% positivity, respectively. Concerning preservatives, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) 0.02% aq. yielded 5.52 (5.11–5.96)% and MI 0.2% aq. yielded 5.28 (4.94–5.64)% positives. Testing formaldehyde 2% aq. identified almost one percentage point more positive reactions than 1% aq. (2.05 (1.81–2.32)% vs. 1.22 (0.99–1.48)). Positive reactions to the recently added allergens were most frequently seen to propolis (5.47 (5.12–5.84)%) and 2-hydroxyethyl methacrylate (3.63 (3.32–3.96)%). Conclusions: Compared to the previous reporting period, surveillance results with the EBS were mostly stable. The results regarding Quaternium 15 (0.4 (0.29–0.53)% positives) justified its exclusion from the 2023 EBS version.