Patch Test Results With the European Baseline Series, 2021/2022—Joint European Results of the ESSCA A and the EBS B Working Groups of the ESCD , and the GEIDAC C

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.