Generalized Pustular Psoriasis: A Cost-of-Illness and Health-Related Quality of Life Study in Italy

Abstract

Generalized pustular psoriasis (GPP) is a life‐threatening rare disease, with an estimated prevalence of 1–3 cases per million individuals in Italy. Despite its clinical severity, evidence on the economic impact of GPP remains limited. This study aimed to estimate the annual societal economic burden of GPP in Italy and assess the health-related quality of life (HRQoL) of patients with GPP. A prevalence-based, probabilistic cost-of-illness model was developed using a societal perspective. Data were drawn from primary and secondary sources, including published and grey literature, expert opinion, and a socio-economic questionnaire administered to Italian patients with GPP. Patient-reported HRQoL was assessed using the Psoriasis Disability Index (PDI). Parameter uncertainty was addressed through both deterministic and probabilistic sensitivity analyses. Our study estimated that the annual economic burden per GPP patient in Italy ranged from €24,914 to €25,270 (total societal cost: €2.94–€2.98 million/year), substantially exceeding the costs associated with plaque psoriasis. While the majority of costs were attributable to the consumption of healthcare resources, more than one-third of the total burden was due to indirect costs. PDI data revealed a high level of perceived disability among patients with GPP, particularly in relation to daily activities and interpersonal relationships. Our analysis indicates that GPP imposes a considerable societal economic burden in Italy and markedly affects patients’ quality of life. The substantial direct and indirect costs of GPP, which far exceed those of plaque psoriasis, underscore the importance of recognizing GPP as a distinct clinical entity rather than a subtype of plaque psoriasis. This distinction could support the development of more targeted management strategies and health policies for GPP (as a rare disease), including disease-specific treatment approvals and reimbursement.