Background: The prevalence of body piercing and orthodontic treatment has increased during recent decades. Such changes in lifestyle may influence the occurrence of nickel allergy.
Objectives: The aim of this study was to describe the prevalence of nickel allergy in a Swedish youth population.
Methods: In a cross-sectional survey, 6095 adolescents answered a questionnaire on their lifestyle and medical history, and 4439 consented to patch testing for contact allergy. Patch test results were adjusted for dropouts by a missing value analysis.
Results: The prevalence of self-reported dermatitis from contact with metal items was 14.8%. Patch testing showed nickel sensitization in 9.9% of the subjects, and in significantly more girls than boys, 13.3% versus 2.5%, respectively. Taking the dropout into account, the estimated true prevalence of nickel sensitivity evaluated by test reading at D4 is 11.8% in girls and 1.6% in boys.
Conclusions: The prevalence of nickel sensitization was higher for girls and slightly lower for boys compared with previous Swedish data. Self-reported information on metal dermatitis as an estimate of nickel allergy has low validity. When possible, missing value analysis should be performed to account for dropouts.