Results of patch testing to the European Baseline Series in adult patients in Turkey: a five-year experience at a tertiary reference center

Introduction:
Allergic contact dermatitis (ACD) is increasing in frequency and has a negative impact on the quality of life. Patch testing is recommended, especially in treatment-resistant cases, atypical cases, workers with hand eczema, and before starting systemic treatment.

Aim:
To report the results of patients with ACD who underwent the European Baseline Series at our tertiary referral hospital.

Material and methods:
All patients diagnosed with ACD who underwent patch testing between 2018 and 2023 were included in the study.

Results:
Between January 2018 and May 2023, 383 patients aged over 18, underwent patch testing with the European Baseline Series (EBS). Of these, 216 (56.3%) patients underwent EBS, while 167 (43.7%) patients underwent the European Patch Series, consisting of 32 allergens applied in our clinic between April 2021 and June 2023. Nickel sulphate was the most common allergen with a positivity rate of 22% (85), followed by gold sodium thiosulfate at 7% (27), cobalt chloride at 6.8% (26), thiomersal and para-phenylenediamine at 4.7% (18), and potassium dichromate at 4.4% (17). In all years, patch test positivity was statistically higher in women than in men. Nickel sulphate and potassium dichromate were statistically significantly more positive in women and men, respectively. Wool wax alcohols, carba mix, cl-me-isothiazolinone, thiomersal positivity decreased over time, while colophony positivity increased significantly over time.

Conclusions:
In this study, although the allergens found positive in the European patch test at our reference hospital were similar to previous studies, it was noteworthy that they changed over time.