Epidemiology and Severity of Prurigo Nodularis in Europe: A Literature Review with an Application to Italian Data.

Introduction: Prurigo nodularis (PN) is a chronic inflammatory skin disease with recent definition and relatively low prevalence. Information on PN, including its epidemiology, severity, and burden of disease is still scanty. Objectives: We sought to review and summarize recent quantitative data on PN in Europe, and to estimate the burden of disease in Italy with a focus on moderate-to-severe PN. Methods: We conducted a systematic literature review of recent studies on the epidemiology of PN in Europe, using PubMed/Medline and EMBASE. The study selection process was conducted independently by 2 reviewers. Articles focused on the severity of PN were also searched, and relevant information was extracted. Synthetic results were combined to population data to derive the best estimate of the burden of PN in Italian adults. Results: Five articles reporting data on incidence and/or prevalence of PN in European populations were identified. The prevalence of PN ranged from 6.5 to 111.0 cases per 100,000, with a median estimate of 32.7 cases per 100,000, the incidence ranging between 2.88 and 20 per 100,000 person-years. Five (other) studies reported data on the severity of PN, measured through pruritus scores, quality-of-life indexes and/or percentage of non-response to treatment. We estimated a total of 16,280 prevalent PN cases in Italy, of whom 6,073 had moderate-to-severe to very severe disease. Among the latter, 1,798 estimated cases were not controlled by standard treatments. Conclusions: We retrieved and summarized recent epidemiological data on PN, evidencing a high burden of disease in Italy and other European countries.