Patch Testing With Cobalt in Adults: A North American Contact Dermatitis Group Experience, 2001-2018.

Background

Cobalt is a recognized cause of allergic contact dermatitis (ACD); however, detailed information on patient characteristics, sites, and sources is lacking.

Objective

The aim of the study is to assess trends in patch test reactions to cobalt and associated patient characteristics, common sources, and body sites affected.

Methods

The study used a retrospective analysis of adult patients who were patch tested to cobalt by the North American Contact Dermatitis Group between 2001 and 2018 (n = 41,730).

Results

Overall, 2986 (7.2%) and 1362 (3.3%) had allergic or currently relevant patch test reaction to cobalt, respectively. Patients with versus without an allergic patch test reaction to cobalt were more likely to be female, employed, have a history of eczema or asthma, be Black, Hispanic, or Asian, and have occupational-related dermatitis. The most commonly identified sources of cobalt in allergic patients included jewelry, belts, and cement, concrete, and mortar. Affected body site(s) varied by cobalt source among patients with currently relevant reactions. Occupational relevance was found in 16.9% of patients with positive reactions.

Conclusions

Positive patch test reactions to cobalt were common. The most common body sites were the hands, and affected site varied by the source of cobalt.