Abstract
Background: Omalizumab, an anti-IgE monoclonal antibody, is an effective treatment for patients with chronic spontaneous urticaria (CSU) resistant to antihistamines, but about 10% are unresponsive. Our aim was to assess the effectiveness, safety, and drug survival (DS) of omalizumab by considering clinical and laboratory characteristics. Methods: We conducted a retrospective study on 296 patients with severe CSU treated with omalizumab. Disease activity, comorbidities, and serum levels of total IgE and anti-thyroid autoantibodies were evaluated over a period of up to 8 years. DS was analyzed using unadjusted Kaplan-Meier survival curves. When applicable, the risk of discontinuation was assessed using Cox regression analysis. Results: Out of 296 patients, 118 (40.4%) were early responders, 72 (25.0%) were late responders, 76 (26.0%) were partial responders, and 25 (8.6%) were non-responders. Early responders were more likely to be patients without associated inducible urticaria (p = 0.021, χ(2) = 9.692), without autoimmune thyroiditis (p = 0.007, χ(2) = 12.037), and those with higher IgE levels (p = 0.039, χ(2) = 8.385). Overall, DS was 53.5% at 8 years, primarily due to clinical remission. DS due to inefficacy and clinical remission were 83.9% and 62.1%, respectively, at 8 years. No patients discontinued omalizumab due to adverse events. Patients with normal IgE levels (p = 0.012, HR = 4.639, CI: 1.393-15.445) and those with autoimmune thyroiditis (p = 0.028, HR = 3.316, CI: 1.128-8.718) had a higher risk of discontinuing omalizumab due to inefficacy. Conclusions: This study confirms the long-term effectiveness and safety of omalizumab in the treatment of CSU over a period of up to 8 years. Most patients discontinued omalizumab due to clinical remission, while only 5.1% discontinued it due to ineffectiveness.