Patients with negative patch tests (NPTs) have distinct characteristics, according to a recent study, which includes being male, aged ≤40 years, and non-Caucasian. Researchers conducted a retrospective cross-sectional analysis of 34,822 patch tested patients. NPTs were defined as negative or irritant final interpretations of all North American Contact Dermatitis Group (NACDG) screening allergens and no relevant allergens on supplemental series. They found:
- Almost one-third (n=10,888, 31.3%) of patients had negative results.
- NPT patients were significantly more likely to have dermatitis primarily involving the following body sites: scattered generalized, lips, or eyelids.
- However, absolute differences in age, race, and site were small and may not be clinically meaningful.
- NPT patients were significantly less likely to have occupationally related skin disease.
- Overall, 8.3% of NPT patients had occupationally related skin disease with precision production workers/machine operators (28.5%), healthcare workers (17.0%), and mechanics/repairers (7.5%) being the most commonly related occupations.
- 22.9% of NPT patients had relevant irritants and 41.6% of irritants were occupationally related; cosmetics/health care products and soaps were common sources for both occupationally related and non-occupationally related irritants.
Warshaw EM, Zhang AJ, Belsito DV, et al. Patients with negative patch tests: Retrospective analysis of North American Contact Dermatitis Group (NACDG) Data 2001-2016. [Published online ahead of print January 10, 2019]. J Am Acad Dermatol. doi:10.1016/j.jaad.2018.12.062.
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