The Burden of Prurigo Nodularis

Prurigo nodularis (PN) is a chronic skin disorder characterized by multiple firm nodular lesions, often symmetrically distributed on areas of the skin that are accessible to scratching.¹ A history of scratching, picking, or rubbing has been identified as one of the core symptoms of PN and can have a notable impact on patient quality of life.²

PN can be mistaken for various disorders, including Kyrle disease, bullous pemphigoid, neurotic excoriations, hypertrophic lichen planus, and atopic dermatitis with lichen simplex chronicus.¹ When assessing skin biopsy results, histopathologic features such as pseudoepitheliomatous hyperplasia, hypergranulosis in the epidermis, focal parakeratosis, and thick compact orthohyperkeratosis can be characteristic of PN.¹

The pathophysiology of PN is not fully understood but current evidence suggests that its underlying mechanism stems from the intersection of neural dysregulation and immunological dysfunction.³ Translational studies over the past 15 years have revealed new insights into the pathogenesis of the disease, leading to the identification of specific immunological pathways that play an important role in the disease.² Specifically, Th2-associated cytokines such as IL-31 and IL-4 have been identified as therapeutics targets, leading to the FDA approval of the IL-4 and IL-13 inhibitor dupilumab (Dupixent) in 2022 and the IL-31 inhibitor nemolizumab (Nemluvio) in 2024, both indicated for the treatment of adult patients with PN.

As more therapeutic options become available for PN, a high need remains for increased awareness of the disease and its impact, which could yield earlier and/or more accurate and diagnosis and treatment. To that end, inquiries into the impact of PN have increasingly articulated its economic, comorbidity, and quality of life burden.

According to findings published in 2023, patients with PN have been found to have higher rates of comorbidities, including not only atopic dermatitis but also chronic hepatitis C, chronic kidney disease, congestive heart failure, chronic obstructive pulmonary disease, depression, and type 2 diabetes.⁴ Findings from a recent retrospective analysis presented at the 2024 Fall Clinical Dermatology Conference showed that patients were more likely to have been newly diagnosed with a comorbidity vs matched controls. Among comorbidities identified in patients with PN were other dermatologic conditions (such as atopic dermatitis), as well as attention-deficit/hyperactivity disorder, autism, autoimmune disease, metabolic disease, and sleep disorders.⁵ Patients with PN were also found to have significantly higher costs, likely exacerbated by the increased prevalence of comorbidities. These results echo previously published data showing that patients with PN are also more likely than the general population to have longer hospital stays and increased cost of care.⁶

One key observation from the investigators of the recently presented data at Fall Clinical Dermatology Conference is that many patients with PN are receiving treatment for the mental health symptoms of PN, while many could benefit from treatments that address autoimmune and inflammatory aspects of the disease. They also highlighted the need for more effective measures to address these burdens in this patient population.⁵

Given the increased knowledge regarding the pathogenesis of PN as well as the associated economic, comorbidity, and quality-of-life burden on patients, the need for greater awareness of the disease in the clinical community and among patients is clearer. As we learn more about the mechanisms of disease, patients must be educated about their disease, the importance of appropriate treatment, and the availability of systemic agents that may offer benefits.

One organization that is raising awareness about PN is the Prurigo Nodularis League, which was founded in 2014 and serves as a mutual platform for clinicians and patients to raise global awareness and provide news relating to PN. League members are regularly informed about the results of current studies and news about diagnostics and treatment. Visit www.pruritussymposium.de for more information.

The next article in this series on prurigo nodularis will explore the data for available and emerging systemic agents.

References:

1. Elmariah S, Kim B, Berger T, et al. Practical approaches for the diagnosis and management of prurigo nodularis: United States expert panel consensus. J Am Acad Dermatol. 2021;84(3): 747-760. doi:10.1016/j.jaad.2020.07.025
2. Müller S, Zeidler C, Ständer S. Chronic prurigo including prurigo nodularis: new insights and treatments. Am J Clin Dermatol. 2024;25(1):15-33. doi:10.1007/s40257-023-00818-z
3. Labib A, Ju T, Vander Does A, Yosipovitch G. Immunotargets and therapy for prurigo nodularis. Immunotargets Ther. 2022;11:11-21. doi:10.2147/ITT.S316602
4. Joel MZ, Hydol-Smith J, Kambala A, Cornman H, Kwatra SG. Prevalence and comorbidity burden of prurigo nodularis in United States adults enrolled in All of Us research program. J Am Acad Dermatol. 2023;89(5): 1056-1058. doi:10.1016/j.jaad.2023.06.045
5. Elmariah SB, Princic N, Richards M, et al. Economic and comorbidity burden of prurigo nodularis and drivers of higher healthcare costs in the US: a retrospective analysis of claims data of patients diagnosed between 2017 and 2022. Poster presented at: 44th Annual Fall Clinical Dermatology Conference; October 24-27, 2024; Las Vegas, NV
6. Whang KA, Kang S, Kwatra SG. Inpatient burden of prurigo nodularis in the United States. Medicines (Basel). 2019;6(3): 88. doi:10.3390/medicines6030088