Original article
Patients with negative patch tests: Retrospective analysis of North American Contact Dermatitis Group (NACDG) data 2001-2016

https://doi.org/10.1016/j.jaad.2018.12.062Get rights and content

Background

Little is known regarding the characteristics of patients with negative patch test (NPT) results.

Objective

To characterize patients with NPT results.

Methods

Retrospective cross-sectional analysis of 34,822 patch tested patients. NPT results were defined as negative or irritant final interpretations of all North American Contact Dermatitis Group screening allergens and no relevant allergens on supplemental series.

Results

Almost one-third of patients (n = 10,888 [31.3%]) had NPT results. Patients with NPT results were significantly more likely to be male (P < .0001), be age 40 years or younger (P = .0054), be nonwhite (P = .0005), and have dermatitis primarily having a scattered generalized distribution (P = .0007) or primarily located on the lips (P = .0214) or eyelids (P = .0364). However, the absolute differences in age, race, and site were small and may not be clinically meaningful. Patients with NPT results were significantly less likely to have occupationally related skin disease (P < .0001). Overall, 8.3% of patients with NPT results had occupationally related skin disease, with precision production worker/machine operator (28.5%), health care worker (17.0%), and mechanic/repairer (7.5%) being the most commonly related occupations. In all, 22.9% of patients with NPT results 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.

Limitations

Retrospective cross-sectional study of tertiary referral population.

Conclusions

Patients with NPT results have distinct characteristics.

Section snippets

Database

This study was approved by the Minneapolis Veterans Affairs Medical Center's Human Studies Subcommittee. The methods for patch testing, evaluation of reactions, and data recording by the NACDG have been published.7, 8, 9 Allergens (Chemotechnique Diagnostics AB, Malmö, Sweden, and allergEAZE SmartPractice, Calgary, Canada) were applied with Finn chambers (SmartPractice, Phoenix, AZ) and Scanpor tape (Norgesplaster Alpharma AS, Vennesla, Norway). NACDG members collected the following data

Patch test results

Of 34,822 patients tested by the NACDG, 68.7% (n = 23,934) had 1 or more PPT reactions; this included 22,538 patients who had 1 or more positive reaction(s) to NACDG screening allergen(s) and 1396 with positive reaction(s) to only non-NACDG supplemental allergen(s). These 23,934 patients were excluded from the study. The study cohort comprised 10,888 patients with NPT reactions (31.3%).

Demographics

Table I summarizes standardized demographic information (male, occupational dermatitis, atopic dermatitis,

Discussion

This study yielded several key findings. First, approximately one-third of patients referred for patch testing had NPT results (31.3%). Second, patients with NPT results were significantly more likely to be male (P < .0001); be age 40 years or younger (P = .0054); be nonwhite (P = .0005); and have dermatitis primarily with a scattered generalized distribution (P = .0007) or located primarily on the lips (P = .0214), eyelids (P = .0364), or other sites (P < .0001). Third, although patients with

Summary

This study provides a unique insight into an uncharacterized population. We found that almost one-third of patch tested patients had negative results (31.3%). Patients with NPT results were statistically more likely to be male, aged 40 years or younger, and nonwhite. Occupationally related skin disease was less common than in patients with PPT results, but among the patients with NPT results with occupationally related skin disease, the most common occupations were precision production

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  • Cited by (0)

    Funding sources: None.

    Disclosure: Dr Taylor is a consultant for Johnson & Johnson, Bayer, Equinox Group, and Kao Brands and a stockholder for Johnson & Johnson, Express Scripts, Opko Health, and Astra Zeneca; in addition, he is an author for Decision Support in Medicine, and he has a nondependent child who is employed by Pfizer. Dr Zirwas is part owner of AsepticMD; a speaker, consultant, and investigator for Regeneron/Sanofi; a speaker for Genentech/Novartis; a consultant for Fit Bit, L'Oreal, and Menlo; and an investigator for Leo, Janssen, Incyte, Foamix, DS Biopharma, UCB, Pfizer, Lilly, Asana, and Avillion. Dr Warshaw, Mrs Zhang, Dr Mathias, Dr DeKoven, Dr Maibach, Dr Sasseville, Dr Belsito, Dr Fowler, Dr Zug, Dr Fransway, Dr DeLeo, Dr Marks, and Dr Pratt have no conflicts of interest to disclose.

    This material is the result of work supported with resources and the use of facilities at the Minneapolis Veterans Affairs Medical Center. The contents do not represent the views of the US Department of Veterans Affairs or the United States Government.

    Reprints not available from the authors.

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