A study of more than 13 million people in the UK indicated an elevated risk for herpes zoster (HZ) in patients with atopic dermatitis (AD). The association persisted independently of comorbidities and treatments, among other factors, with the risk increasing with increasing AD severity.

“We have known for some time that patients with AD can have increased susceptibility to certain infections, and we also know that some of our systemic treatments can increase the risk of HZ. What is particularly notable here is the suggestion that AD itself may confer some additional risk, independent of those treatments,” Peter Lio, MD, told Medscape Medical News. “Importantly, adjusting for oral corticosteroids and traditional systemic immunosuppressants only modestly changed that association,” added Lio, founder of the Chicago Integrative Eczema Center and clinical assistant professor of dermatology at Northwestern University in Chicago. He was asked to comment on the results and was not involved with the study.

The matched cohort study, published on August 5 in JDDG: Journal der Deutschen Dermatologischen Gesellschaft, used primary care data from a UK research database of 14,081,774 observations from 13,426,267 people: 11,636,684 observations from participants who did not have AD and 2,445,090 from participants with AD.

Investigators found a 28% increased risk for HZ in people with AD after adjusting for age, sex, comorbidities, obesity, and other factors. HZ risk increased with AD severity compared with individuals without AD: mild AD (adjusted hazard ratio [aHR], 1.22), moderate AD (aHR, 1.28), and severe AD (aHR, 2.33).

When adjusting for topical corticosteroid use, HZ risk was higher in those with AD (aHR, 1.17). The study used treatments as a proxy for disease severity, the study authors noted.

“It is unclear from their study if it is the disease severity itself or the treatment that is leading to increased HZ risk with increasing AD disease severity,” said Theodora K. Karagounis, MD, assistant professor of dermatology at NYU Grossman School of Medicine in New York City, who was not an investigator and was asked to comment on the results. “Still, when excluding treatments, they find AD is associated with HZ,” she told Medscape Medical News.

Age was also a key factor associated with increased HZ risk. HRs were highest among individuals aged 30-40 years (HR, 1.51), followed by those aged 40-50 years (HR, 1.42), and consistently declined among older age groups: HR, 1.29, in patients aged 50-60 years and was lowest among those aged 70-80 years (HR, 1.23).

The finding, experts noted, could be a result of the lower absolute incidence of HZ in younger populations: from 1.58 events per 1000 person-years among individuals younger than 30 years to 8.85 events per 1000 person-years among those aged 80 years or older.

“The interaction the authors observe with age is interesting, with the effect of AD on HZ risk being most pronounced in the younger age groups,” Karagounis said. “Notably, this may just reflect that young people overall have a low risk for HZ and so just a few more added cases due to the added risk with AD gives a higher hazard ratio as compared to older people.”

The findings, Karagounis said, present new potential avenues for research. One possible subject is dupilumab, a common AD treatment that has also been shown to reduce the risk for HZ.

“Does HZ in AD patients take longer to resolve? Do we need to be treating with valacyclovir for longer?” Karagounis asked. “This study just looked at first episodes of HZ. How frequently do patients with AD get HZ ?.... We should [also] investigate the risk of HZ in AD patients who have received zoster vaccination and see if that modifies the risk/number of outbreaks.”

Lio said the study should be treated as added potential motivation to vaccinate for HZ as appropriate.

“For me, the practical takeaway is not that we should alarm our patients with AD about shingles,” he said, “but that we should recognize another potentially preventable complication and keep vaccination and infectious-risk assessment in mind as part of thoughtful, comprehensive AD care.”

None of the study authors had disclosures. No funding source was listed. Karagounis had no relevant disclosures. Lio’s disclosures included speaking, advising, consulting, and educational activities with pharmaceutical, biotechnology, dermatology, consumer health, and skin-care companies or organizations including AbbVie, Apogee Therapeutics, Arcutis Biotherapeutics, Eli Lilly, Galderma, Incyte, Kenvue, L’Oréal Groupe, Nektar Therapeutics, Pfizer, Regeneron/Sanofi, Skinfix, Sun Pharma, and Verrica Pharmaceuticals. In addition, Lio reported ownership or investment interests in 11 companies, namely, Alphyn Biologics, Codex Labs, Concerto Biosciences, LearnHealth, Medable, Modernizing Medicine, Soteri Skin, Stratum Biosciences, Thimble Health, Verdant Scientific, and Yobee Care.

Scott Harris has covered dermatology and other areas of healthcare for more than a decade. He lives near Washington, DC.