Associations of Nickel Co-Reactions and Metal Polysensitization in Adults

Background Allergic contact dermatitis to metals is a significant clinical and public health problem. Little is known about the determinants of polysensitization to metals. Objective The aim of the study was to determine the frequency and predictors of nickel co-reactions and metal polysensitization. Methods This is a retrospective chart review of 686 adults (age ≥ 18 years) who were patch tested from 2014 to 2017. Results Overall, 267 patients (38.9%) had 1 or more positive patch-Test reactions to a metal allergen, most commonly nickel (17.4%), mercury (12.3%), and palladium (9.2%). Nickel reactions were inversely associated with age (logistic regression; adjusted odds ratio [95% confidence interval], 0.39 [0.29-0.78]). Among patients with positive reactions to nickel, 34.5%, 15.1%, and 5.0% had positive reactions to 1, 2, or 3 additional metals, respectively. The most common nickel co-reactors were palladium, mercury, and gold. Polysensitization to metals occurred in 11.8% of patients. Polysensitization to metal allergens was associated with female sex (6.67 [1.01-44.21]) and inversely associated with age (0.40 [0.18-0.88]). Conclusions Nickel-sensitized patients have high rates of metal co-reactions. Polysensitization to metals is common in adults. These results may help guide future strategies for allergen avoidance.