Nickel allergy is of significant public health importance in North America and the frequency of nickel sensitivity in patients referred for patch testing has significantly increased over a 20-year period. This according to a recent study that sought to examine the epidemiology of nickel sensitivity in North America. Researchers conducted a retrospective, cross-sectional analysis of 44,097 patients patch tested by the North American Contact Dermatitis Group from 1994-2014. They evaluated frequency of nickel sensitivity and patient demographics. For each positive nickel reaction, they tabulated clinical relevance, occupational relatedness, and exposure sources. They found:

• Average frequency of nickel sensitivity was 17.5% (1994-2014).
• Nickel sensitivity significantly increased over time (14.3% 1994-1996 to 20.1% 2013-2014).
• Nickel sensitive patients were significantly more likely to be female, young, non-Caucasian, atopic (eczema and asthma), and/or have dermatitis affecting the face, scalp, ears, neck, arm, or trunk.
• Overall, 55.5% of reactions were currently clinically relevant; this frequency significantly increased over time (44.1% 1994-1996 to 51.6% 2013-2014).
• Occupational relatedness was 3.7% overall with a significant decrease over time (7.9% 1994-1996 to 1.9% 2013-2014).
• Jewelry was the most common source.