Nickel allergy as risk factor for hand eczema: a population-based study

Summary Background In population‐based studies using self‐reported nickel allergy, a hand eczema prevalence of 30–43% has been reported in individuals with nickel allergy. In a previous Swedish study, 958 schoolgirls were patch tested for nickel. In a questionnaire follow up 20 years later no association was found between nickel allergy and hand eczema. Objectives To investigate further the relation between nickel allergy and hand eczema. Methods Three hundred and sixty‐nine women, still living in the same geographical area, now aged 30–40 years, were patch tested and clinically investigated regarding hand eczema. Results Patch testing showed 30·1% nickel‐positive individuals. The adjusted prevalence proportion ratio (PPR) for hand eczema after age 15 years in relation to nickel patch test results was 1·03 (95% confidence interval, CI 0·71–1·50). A history of childhood eczema was reported by 35·9%, and the PPR for hand eczema in relation to childhood eczema was 3·68 (95% CI 2·45–5·54). When analysing the relation separately in women with and without a history of childhood eczema a statistical interaction was found. The hand eczema risk was doubled in nickel‐positive women without a history of childhood eczema, with a PPR of 2·23 (95% CI 1·10–4·49) for hand eczema after age 15 years. Conclusions A doubled risk for hand eczema was found in nickel‐positive women without a history of childhood eczema. When analysing all participants, there was no statistically significant difference between nickel‐positive and nickel‐negative women regarding occurrence of hand eczema. The most important risk factor for hand eczema was childhood eczema. The risk for hand eczema in nickel‐positive women may previously have been overestimated.