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

## TL;DR

This study found that self-reported nickel allergy among children decreased over time, but remained high in those with atopic dermatitis, with ear piercing and being female as key risk factors.

## Contribution

The study provides new insights into the changing prevalence of nickel allergy and its association with atopic conditions and gender over nearly two decades.

## Key findings

- Self-reported nickel allergy decreased from 7.7% in 2006 to 6.1% in 2017.
- Children with atopic dermatitis had consistently higher rates of nickel allergy over time.
- Ear piercing and female sex were strong risk factors for nickel allergy.

## Abstract

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.

Nickel allergy is the most common contact allergy and studies on prevalence and risk factors are important in the preventive work of contact allergies. In the present study with 3 child cohorts included in 1996, 2006, and 2017, self-reported nickel allergy and risk factors were investigated. We found a decreased prevalence of self-reported nickel allergy, but not among children with atopic dermatitis. Self-reported nickel allergy was significantly more common among children with atopic dermatitis. We also found an association between self-reported nickel allergy and allergic rhinitis. Ear piercing and female sex were the strongest risk factors for self-reported nickel allergy.