Hand Eczema Referred for Patch Testing: Retrospective Study in Shanghai, China From 2018 to 2023

Hand eczema (HE) imposes a significant socioeconomic burden, particularly in severe and occupational cases. To identify major allergens and associated factors in Chinese patients with HE referred for patch testing, we conducted a retrospective cohort study included 788 cases of HE detected from 4438 patients who were patch-tested in Shanghai, China, between 2018 and 2023. The HE group had an 82.23% patch-test positivity rate. N-Isopropyl-N-Phenyl-4-Phenylenediamine were more common in the HE than in the non-HE group after false discovery rate (FDR) correction (FDR-adjusted p < 0.05), while other rubber allergens showed similar trends (multivariable-adjusted p < 0.05). The top five allergens associated with HE were nickel sulfate, dodecyl gallate, methylisothiazolinone, cobalt chloride, and methylisothiazolinone/methylchloroisothiazolinone. Polysensitization was more common in females than in males, while sensitivity to occupation-related allergens was more common in males. Fragrance allergies were more frequent in patients over 40 years old, and those with a history of atopic dermatitis showed no significant allergen trends. Among occupational exposures, hairdressers and beauticians showed heightened hand sensitivity to preservatives and p-phenylenediamine. Although few allergens reached significance after FDR correction in other occupations, multivariable-adjusted analyses suggested certain allergens as potentially occupational, warranting further surveillance. These findings highlight the notable difference in positive patch test reactions between individuals with HE and without HE and emphasize the role of allergens in HE, as well as the risks posed by sex, age, history of allergic dermatitis, and occupation. Further studies with balanced samples are warranted.