Chronic Spontaneous Urticaria in Finland - A Nationwide Registry Study on Epidemiology and Treatment Patterns in Secondary Care.

Chronic spontaneous urticaria (CSU) is a burdensome skin disease characterized by recurrent wheals and/or angioedema without identifiable external triggers, with symptoms lasting for six weeks or longer, and impairs patients' quality of life and work productivity. This nationwide registry-based study examined epidemiology of CSU in Finland and its treatment patterns. Using secondary care data from 2001 to 2023, we identified 8,784 adult patients with CSU; 70% were female and the mean age was 45.3 years. Point prevalence of CSU was 0.21% in 2022 and an age-standardized incidence 9.34 per 100,000 person-years. A total of 85.8% of patients received antihistamines and 36.1% of all patients required concurrent corticosteroids, suggesting suboptimal disease control. Only 8.5% of patients received omalizumab, and the median time from antihistamine initiation to omalizumab was 9 Comorbidities such as asthma, hypertension, and depression were common. The low recorded of angioedema (5.9%) likely reflects limitations in registry coding. Overall, these findings highlight gaps in CSU management, including delayed initiation of omalizumab and a high proportion of systemic corticosteroid use. These patterns may partly reflect omalizumab reimbursement restrictions and delays in patient pathways, and suggest opportunities to improve clinical practice and patient outcomes.