As many as 16.5 million adults in America have atopic dermatitis (AD).

This estimate comes from a new study from the Perelman School of Medicine at the University of Pennsylvania, which also projected 6.6 million of these adults have disease that would be classified as moderate to severe, leading to a decrease in quality of life. The new findings appear in the Journal of Investigative Dermatology.

To arrive at their findings, researchers surveyed 1,278 adults sampled from the GfK Knowledge Panel, a probability-based online panel that is thought to be representative of the adult population of the United States. Among those respondents, 7.3 percent met the criteria for diagnosis of AD. Sixty percent of those with AD classified as mild, 29 percent as moderate, and 11 percent as severe. Since the panel is representative of the country’s population, researchers used U.S. census population data to project that 16.5 million American adults are living with AD, with 6.6 million of those cases being moderate-to-severe. Patients with AD and those with more severe disease also had higher scores in other patient-reported outcome measures, including the Dermatology Life Quality Index, indicating a worse impact on quality of life and an increased likelihood of anxiety or depression as measures by the Hospital Anxiety and Depression Scale.

“We tend to think of this disease as a children’s disease, but our data show that’s not the case,” says the study’s lead author Zelma C. Chiesa Fuxench, MD, MSCE, an assistant professor of Dermatology at Penn, in a news release. “Our findings show this disease affects seven percent of the population, far more than other inflammatory conditions like psoriasis, which only affects about three percent. Yet psoriasis has eight biologic treatments available for patients, whereas atopic dermatitis only has one that’s approved.”

“These findings show a disconnect between the prevalence of this disease – and its impact on patient quality of life – compared to the resources being dedicated to developing systemic therapies,” Dr. Chiesa Fuxench says. “With only one approved biologic available, it’s clear the need is not being met.”

Dr. Chiesa Fuxench says the numbers also hint at larger questions about this population, including whether they developed the condition as they got older or whether they had it as children and stopped seeking treatment at some point during their lives due to unhappiness with or poor response to currently available therapies. Many patients, she notes, are told they will grow out of the disease, but these data suggest that may not be the case, and that the disease may change over time. She also notes the medical and social impact of AD can also lead to a financial impact for many patients.

“When these patients experience flare ups, they’re more likely to call out of work, avoid going out, or remove themselves from other situations they might typically enjoy,” she said. One study from 2017 estimates the annual cost of AD in the United States is $5.3 billion each year, which only further drives home the point.

“Topical and oral corticosteroids don’t work for everyone, and even when they do, patients should not be on them long-term,” Dr. Chiesa Fuxench says. “We need to prioritize our understanding of this complex disease as well as the development of innovative therapies for these patients.”

The study’s senior author was Peck Ong, MD, an associate professor of Clinical Pediatrics at the Keck School of Medicine of the University of Southern California and an attending physician at Children’s Hospital Los Angeles.

This study was completed in collaboration with the Asthma and Allergy Foundation of America in partnership with the National Eczema Association, sponsored by Sanofi Genzyme and Regeneron. Sanofi Genzyme and Regeneron manufacture dupilumab, but had no involvement in this research.