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.