Epidemiology, characteristics of disease and unmet needs of patients with generalized pustular psoriasis: a large Italian Delphi consensus

Introduction: Generalized pustular psoriasis (GPP) is a rare and chronic, debilitating skin condition characterized, in its acute flare phase, by clinically severe and potentially lifethreatening systemic manifestations. Data on GPP are still scanty, particularly in Europe and at a national level. The aim of this study was to provide expert indications on several disease-related and patient-related aspects of GPP, with specific focus to the Italian context. Methods: We conducted an iterative eDelphi study following the recommended criteria for reporting methods and results. After a thorough bibliographic review aimed to identify unknown or controversial issues in GPP, the following areas were investigated through a few specific questions/statements for each area: (1) disease epidemiology; (2) disease characteristics, with specific interest toward GPP flares; (3) diagnosis and diagnostic delay; (4) GPP treatment; (5) GPP patient journey and use of healthcare resources in Italy; (6) unmet needs and quality of life. An Executive Board of 9 principal investigators revised and approved the topics to be examined and overviewed the whole project. A total of 35 experts from different Italian areas, including 34 board-certified Italian dermatologists and 1 representative of patients' associations, took part in the study. Results: A high agreement in responses from Italian experts emerged during two eDelphi iterations on - among several other aspects - GPP prevalence and incidence in Italy, use of European Rare and Severe Psoriasis Expert Network diagnostic criteria, flare frequency and duration, best diagnostic and care pathway, and main unmet needs of Italian patients. On the other hand, a broad spectrum of treatments (of different drug classes) was reported both in the acute and chronic phases of GPP, and no consensus on the issue was thus achieved. Conclusions: Consensus findings from this Delphi study of GPP experts may be useful to fill gaps of knowledge and improve awa