Prevalence of contact allergy to metals: nickel, palladium, and cobalt in Southern Sweden from 1995-2016.

Background In 2001, the EU nickel directive was introduced to prevent contact allergy to nickel. Contact allergy to palladium and/or cobalt is often seen together with contact allergy to nickel. Objectives To compare the contact allergy prevalence of nickel, palladium, and cobalt allergy before and after the introduction of the EU nickel directive in consecutive patients with dermatitis. Methods A retrospective analysis of patch test results from 1995-2016 was performed (n = 18 264). Chi-square tests were used to examine trends for nickel, palladium, and cobalt across test years. Logistic regression was used for associations. Results The prevalence of nickel allergy decreased significantly in the youngest age group (6-30 years) for both female and male patients from 1995-1999 to 2012-2016: females: 33.4% to 19.1% (P < .001); males: 5.9% to 2.1% (P < .05). The concomitant reactions between nickel and palladium and nickel and cobalt among young females, respectively, also decreased significantly. Isolated palladium and cobalt allergy remained stable (1.4% and 2.3%, respectively) during the same time period for both men and women. Conclusions The prevalence of nickel has decreased among young females and males suspected of contact allergy in Southern Sweden after the introduction of the EU nickel directive. There has been no change in isolated palladium or cobalt allergy.