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

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. 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 analyzed in relation to treatment outcomes. 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). 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.