A multicenter study by the Brazilian Society of Dermatology on a new standard patch test series.

BACKGROUND

The prevalence of allergic contact dermatitis (ACD) differs across various populations, and the sensitization rate can change constantly as new products are introduced to the market. The current Brazilian standard series of patch tests has been used for over two decades. Therefore, the development of a new Brazilian standard series is important to ensure that contact tests remain a reliable diagnostic tool.

METHODS

A Brazilian multicenter, cross-sectional, prospective study was conducted using a modified series of patch tests between 2023 and 2025. The factors under study were the substances used in the contact tests, and the outcomes were the frequencies of positivity and relevance. Demographic and clinical variables of the participants, who had contact dermatitis without a defined etiology prior to the tests, were evaluated. The required sample size was defined as 523 patients, estimating the prevalence of positivity with a 1.8% confidence interval. Wald's test was considered a 95% confidence level and a 1% expected prevalence of positivity.

RESULTS

A total of 567 participants were included, 77.3% female, with a mean age of 53.3 years, and most belonged to phototypes II, III, and IV. Cleaning services were the most frequent occupational activity, and 43.3% of patients had a personal history of atopy. The overall reactivity of the tests was 69.3%, with 70.2% relevance. Nickel sulfate was the most frequently reactive allergen (28.9%), and 29 substances reached at least 1% positivity.

STUDY LIMITATIONS: Lack of representatives from all regions of Brazil and absence of prospective follow-up.

CONCLUSION

The authors propose a new Brazilian standard series of patch tests, with 40 substances, considering the 29 that achieved 1% positivity and another 11 with clinical importance and supported by current literature as emerging and current allergens.