Study Probes Racial Differences in Prurigo Nodularis, a Debilitating Itch Disease

Prurigo nodularis is one of the most punishing conditions in dermatology, a chronic inflammatory skin disease defined by hard, intensely itchy nodules that patients scratch until the skin breaks down. Now a team of researchers at Rutgers Robert Wood Johnson Medical School and the University of Maryland School of Medicine, including investigators at the Maryland Itch Center, has published a cross-sectional analysis examining how the clinical characteristics and lifestyle factors of the disease differ between Black and white patients. The study, published in Archives of Dermatological Research, draws on the National Institutes of Health’s All of Us Research Program, one of the largest and most diverse biomedical datasets ever assembled in the United States.

The research, led by Gaurav N. Pathak and corresponding author Shawn G. Kwatra, arrives at a moment of growing scientific and commercial interest in prurigo nodularis. For decades the disease was under-recognized, lumped in with generic chronic itch and treated with little more than moisturizers and antihistamines. That changed when the United States Food and Drug Administration approved the first systemic therapies specifically for the condition, transforming it from an orphan diagnosis into a focal point of immunodermatology. Yet as therapeutic options have expanded, a parallel body of evidence has made clear that the burden of the disease is not distributed evenly across populations.

Earlier work cited by the team, including a landmark study of more than 900 prurigo nodularis patients published in the Journal of the American Academy of Dermatology, documented ethnic differences in the comorbidities that accompany the disease. Patients with skin of color have historically faced delays in diagnosis, differences in how the disease presents on darker skin, and unequal access to specialty care, a broader pattern of racial disparity in dermatology that has been catalogued in recent reviews in the same journal. Understanding whether Black and white patients differ in the clinical profile of prurigo nodularis itself, rather than merely in the care they receive, is a critical step toward equitable treatment.

The All of Us Research Program provides an unusually powerful lens for such a comparison. Launched by the National Institutes of Health, the program has enrolled hundreds of thousands of participants across the United States with the explicit goal of reflecting the country’s diversity, collecting electronic health records, survey data on lifestyle and environment, and in many cases genomic information. The dataset is available to registered researchers through the All of Us Researcher Workbench, and the authors of the new analysis have made their data and code available as a featured workspace on that platform, an unusual degree of transparency that allows other investigators to scrutinize and extend their findings.

Cross-sectional designs of this kind compare groups at a single point in time, which makes them efficient for mapping differences in disease characteristics, comorbid conditions, and lifestyle variables such as smoking status, body mass index, and sleep. In prurigo nodularis research, such variables matter enormously. Chronic itch is known to intertwine with metabolic and psychiatric health, and the relentless itch-scratch cycle that defines the disease disrupts sleep, degrades quality of life, and may feed into systemic inflammation. Identifying which of these factors differ by race could point to mechanisms, and to interventions, that are currently being missed.

The study also sits within a rapidly evolving genetic and immunological picture of the disease. A 2023 study published in the Journal of Investigative Dermatology, co-authored by members of the same broader research community, developed a polygenic risk score for prurigo nodularis that predicted racial and genetic susceptibility to the condition, providing evidence that inherited risk contributes to who develops the disease. On the immunological side, prurigo nodularis is now understood as a type 2 inflammatory disorder driven by signaling pathways involving interleukins and neural itch fibers, the same biology targeted by the newest approved drugs.

Cardiovascular health has emerged as another front. A global cohort study published in EBioMedicine in 2024 reported increased cardiovascular risks and mortality among prurigo nodularis patients, suggesting that the disease’s systemic inflammation extends well beyond the skin. If lifestyle and cardiometabolic factors differ between Black and white patients with the condition, as the new cross-sectional analysis set out to test, that could have direct consequences for how clinicians monitor and counsel patients, and for which comorbidities are screened for in different populations.

The research team’s composition reflects the clinical stakes. Kwatra, whose Maryland Itch Center specializes in refractory chronic itch, has received grant funding from the Skin of Color Society and serves as a consultant or advisor to numerous pharmaceutical companies developing itch therapies, including AbbVie, Celldex Therapeutics, Galderma, Incyte, Novartis, Pfizer, Regeneron, and Kiniksa. That combination of academic focus on itch biology and frontline experience with diverse patient populations is precisely the vantage point from which questions about racial differences in disease presentation become answerable rather than anecdotal.

What makes the new analysis notable methodologically is its grounding in a cohort designed for exactly this kind of equity-focused question. Traditional dermatology datasets skew heavily toward white patients seen in academic centers, which has historically limited the generalizability of findings and obscured diseases like prurigo nodularis as they appear in skin of color. By contrast, the All of Us program’s deliberate recruitment of populations underrepresented in biomedical research, combined with its standardized surveys and linked health records, allows investigators to compare clinical characteristics and lifestyle factors across racial groups within a single, consistently measured framework.

The work also underscores a shift in how the dermatology research community approaches itch. Once dismissed as a symptom rather than a disease, chronic itch of the nodular type is now the subject of dedicated research centers, validated severity instruments, targeted biologics, and genetic risk models. The new study’s contribution lies in insisting that this progress be examined through the lens of race, ensuring that as therapies advance, the differences in disease burden, comorbidity patterns, and lifestyle context between Black and white patients are documented rather than assumed. With the data and code publicly available on the All of Us Researcher Workbench, the analysis invites replication and extension, a model of open science for a condition whose true population-level contours are only now coming into focus.

Subject of Research: Racial differences in clinical characteristics and lifestyle factors among patients with prurigo nodularis

Article Title: Differences in clinical characteristics and lifestyle factors between black and white patients with prurigo nodularis patients: a cross-sectional analysis

Article References: Pathak, G. N., Akiska, Y. M., Pathak, S. S., & Kwatra, S. G. (2026). Differences in clinical characteristics and lifestyle factors between black and white patients with prurigo nodularis patients: a cross-sectional analysis. Archives of Dermatological Research, 318(1), Article 504. https://doi.org/10.1007/s00403-026-04912-0

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04912-0

Keywords: prurigo nodularis, chronic itch, racial disparities, dermatology, All of Us Research Program, skin of color, health equity, cross-sectional study, comorbidities, lifestyle factors, type 2 inflammation, polygenic risk score