Low Total IgE Predicts Non-Response to Omalizumab in Chronic Spontaneous Urticaria: A 10-Year Real-Life Study.

Introduction: Omalizumab is an effective add-on therapy for chronic spontaneous urticaria (CSU) refractory to antihistamines. However, biomarkers predicting treatment response remain unclear. This 10-year real-life, retrospective study aimed to assess the efficacy and safety of omalizumab in CSU and to identify predictors of treatment response, particularly focusing on total IgE levels.

Methods: We included 221 adult CSU patients treated with omalizumab between 2015 and 2024. Clinical response was evaluated using Urticaria Activity Score over 7 days (UAS7) and Urticaria Control Test (UCT). Treatment response was categorized as rapid, late, or non-response. Laboratory parameters, including total IgE, eosinophils, and thyroid autoantibodies, were analysed in relation to treatment outcomes.

Results: Omalizumab provided rapid or late responses in 98.2% of patients, with significant reductions in UAS7 and improvements in UCT scores over time. Only 1.8% were non-responders. A total IgE level ≤12.5 IU/mL was identified as a strong predictor of non-response (AUC: 0.903), with 75.0% sensitivity and 96.7% specificity. Multivariate logistic regression revealed that lower total IgE levels independently predicted non-response (OR: 0.032, p = 0.031).

Conclusion: Omalizumab is effective and safe in real-life CSU management, even among patients with comorbidities such as autoimmune diseases and malignancies. Low total IgE levels may serve as a reliable biomarker for predicting non-response and guiding individualized treatment strategies.