Middle-Aged, Older Adults More Likely to Test Positive on Skin Patch Testing

Credit: Pexels / Towfiqu barbhuiya

The prevalence of skin sensitization relevant to allergic disease could vary for patients based on their age, according to findings from a new study.¹

A prospective analysis from investigators in Spain found that middle-aged adults who undergo patch testing to diagnose contact dermatitis are significantly more likely to test positive than younger adults. The findings suggest the effect of cumulative lifetime exposure to haptens and exacerbations of allergic disease may be more significant than previously thought, and reinforce the need to conduct baseline path test series in patients with suspected contact dermatitis regardless of their age.

The trend of age-associated risk of contact dermatitis is an increasingly understood phenomenon; even at the pediatric level, investigators have interpreted an association between specific risks and children’s age.²

The Spanish team of investigators conducted a prospective, multicenter study using cohorts from a national contact dermatitis register to assess the results of patch tests for skin sensitizations and their relevance and association with age groups. As the team noted, some factors for sensitization are age-related—prompting the ask of whether different age groups present with unique sensitivities.¹

“Occasionally, no prevalence differences have been found between the most frequent haptens when comparing cohorts of children/adolescents and/or adults,” investigators wrote. “The analysis of patch testing features (relevance, degree of positivity) by age has seldom been evaluated, even if it has been suggested that the probability of a positive reaction being relevant is lower for children as well as less intense reactions when patch testing elderly patients.”

Investigators used data from patients patch-tested between 2019 and 2023, including test readings at days 2, 4 and occasionally 7. They evaluated for relevance to age after clinical examination and history of previous exposures per patient. Skin sensitization was defined as ≥1 positive patch test reaction. Polysensitization was defined as ≥3 positive reactions.

The team further collected data on the nature of the reaction; its relevance in timing; patient age, gender, occupational dermatitis and atopic dermatitis; affected sites of the body; and symptoms. Age groups were stratified by children (0 – 11 years); adolescents (12 – 18 years); young adults (19 – 30 years); middle-aged adults (31 – 65 years) and older adults (≥66 years).

The final cohort included 13,368 patients who were patch-tested during the observed period. Only 30.3% were identified as male; 18.1% had atopic dermatitis and 9.1% had occupational dermatitis. Dermatitis was most frequently present on the hands (30.9%) and face (23.7%). Approximately two-thirds (67.8%) of patients were aged >40 years.

The breakdown of patients per age group were as follows:

• Children (n = 229 [1.71%])
• Adolescents (n = 484 [3.62%])
• Young adults (n = 1741 [13.02%])
• Middle-aged adults (n = 8241 [61.65%])
• Older adults (n = 2673 [20.0%])

More than 45% (n = 6069) patients presented with ≥1 positive reaction on the skin patch tests. The investigators observed differences in positive patch test results and relevance by age cohorts, with the great proportion of affected patients being middle-aged adults.

Middle-aged adults were 41% more likely to report a positive result compared with young adults (odds ratio [OR], 1.41; 95% CI, 1.26 – 1.58), while older adults were 15% more likely to report a positive result compared with young adults (OR, 1.15; 95% CI, 1.01 – 1.32), when adjusted for variables including sex, atopic or occupational dermatitis status, and body location.

Investigators additionally observed age-based differences in trends for nickel, potassium dichromate, caines, colophony, Myroxylon pereirae resin, 2-hydroxyethyl methacrylate and limonene hydroperoxide sensitizations based on patient age groups. “Most haptens with trend differences in relevance also associated differences in frequency of skin sensitization pattern by age group,” they noted.

Other variables that were found to impact prevalence of positive skin patch results were male sex, atopic dermatitis status and facial dermatitis (versus hands)—each was linked with a significantly reduced risk of positive results. Contact dermatitis was associated with a two-fold increased risk of a positive result.

In reviewing the findings, investigators said the data may “reinforce the progressive increase in prevalence of skin sensitization with age, with a plateau in middle-aged adulthood and a subsequent reduction in older adults.”

“An increased cumulative lifetime exposure of haptens as well as different exposure patterns between age groups could explain the increase from adolescence to adulthood,” they wrote. “In fact, it is frequent to detect skin sensitization in adults to a hapten to which the patient has been exposed intermittently thorough life, without any previous reaction.18 In addition, this is complemented by both occupational factors and sociodemographic habits that may be altered over the course of adulthood.”

References

1. ^{Pesqué D, Planella-Fontanillas N, Borrego L, Sanz-Sánchez T, Zaragoza-Ninet V, Serra-Baldrich E, Miquel-Miquel FJ, Silvestre-Salvador JF, Córdoba-Guijarro S, Sánchez-Gilo A, Mercader-García P, Navarro-Triviño FJ, Ortiz-de-Frutos FJ, Tous-Romero F, Rodríguez-Serna M, Melé-Ninot G, Barrabés-Torrella C, Ruiz-González I, Pastor-Nieto MA, Carrascosa-Carrillo JM, Gómez-de-la-Fuente E, Sánchez-Pedreño-Guillén P, Sánchez-Pérez J, Pereyra-Rodríguez JJ, Gatica-Ortega ME, González-Pérez R, Pujol RM, Descalzo MÁG, García-Doval I, Giménez-Arnau AM. Patch test results to the Spanish baseline patch test series according to age groups: A multicentric prospective study from 2019 to 2023. Contact Dermatitis. 2024 Oct 12. doi: 10.1111/cod.14702. Epub ahead of print. PMID: 39394969.}
2. ^{Kunzmann K. Pediatric Contact Dermatitis Allergens Vary by Age, Sex, Race. HCPLive. Published March 13, 2024. https://www.hcplive.com/view/pediatric-contact-dermatitis-allergens-vary-age-sex-race}