Self-reported Nickel Allergy among Schoolchildren: Trends in Prevalence, Risk Factors, and Atopic Comorbidity.

Nickel allergy is common among children. The present study investigated prevalence trends of self-reported nickel allergy, risk factors, and atopic comorbidity among children. Eight-year-old children from Norrbotten County, Sweden, were recruited in 1996 (n = 3,430), 2006 (n = 2,585), and 2017 (n = 2,785). Self-reported nickel allergy decreased from 7.7% (2006) to 6.1% (2017; p = 0.024) and was significantly more common among girls. In 1996, only children with atopic dermatitis answered questions on nickel allergy. Among children with atopic dermatitis, no significant decrease was seen over the years 1996 to 2017. Ear piercing (odds ratio [OR] 1.93, 95% confidence interval [CI] 1.39-2.68 and OR 5.57, 95% CI 3.71-8.38) and female sex (OR 4.05, 95% CI 2.68-6.13 and OR 1.73, 95% CI 1.09-2.74) were risk factors for self-reported nickel allergy in 2006 and 2017, respectively. Self-reported nickel allergy was significantly more prevalent among children with atopic dermatitis than without in 2006 (12.3% vs 6.4%; p < 0.001) and 2017 (11.5% vs 5.1%; p < 0.001), and among children with allergic rhinitis in 2017 (8.6% vs 4.7%; p = 0.015). In conclusion, we found a decreasing prevalence of self-reported nickel allergy, but not among children with atopic dermatitis. Ear piercing and female sex were strongly associated with nickel allergy. Our findings also suggest that nickel allergy is associated with atopic dermatitis and allergic rhinitis.