Positive Allergen Patch Test More Likely With Atopic Dermatitis

Patients with atopic dermatitis (AD) have a higher rate of positive patch tests, especially to cosmetics and medicaments, than the general population, according to a research letter published in the Journal of the American Academy of Dermatology.

Researchers conducted a retrospective study to evaluate patients with AD (n=5641) and without AD (n=10,096) who underwent a patch test between 2016 and 2020 for the rates of allergic contact dermatitis (ACD), or positivity within 3 days of the test.

Among participants in the AD and control groups, mean age was 53.51 (SD, 21.1) and 55.45 (SD, 19.2) years (P <.0001), 69.0% and 74.9% were women (P <.0001), and 68.4% and 72.0% were White (P <.0001), respectively.

The prevalence of ACD was higher in participants in the AD group (54.8%) compared with those in the controls (47.3%; P <.0001).

Those with AD were more likely to test positive to patch tests for cosmetics (7.0% vs 5.7%; P =.0007), drugs (2.3% vs 1.7%; P =.0204), dyes (1.9% vs 1.4%; P =.0360), food (0.4% vs 0.1%; P =.0030), other chemical products (10.8% vs 8.3%; P <.0001), other agents (10.8% vs 8.6%; P <.0001), and unspecified allergens (34.1% vs 26.1%; P <.0001) compared with control participants, respectively.

Conversely, fewer participants with AD tested positive to metal patch tests (6.2%) compared with control participants (7.1%; P =.0228).

No group differences were observed for the rate of positive patch tests for nonfood plants (1.2%-1.3%; P =.5642) and adhesives (0.6%-0.8%; P =.2056).

Researchers noted that other claims-based data indicated that patients with AD also had higher a likelihood of ACD, but did not proceed to patch testing compared with the general population.

Limitations of the study include the broad categories of allergens and the rate of unidentified allergens.

Study authors conclude, “We found higher rates of positive patch tests in AD patients, especially to cosmetics and medicaments. Our study suggests that claims data may be useful in tracking allergen trends in large populations. This capability will likely improve with the more detailed ACD diagnosis codes of ICD-11. Further study is required.”