Predictors of Super/Poor Omalizumab Response in Chinese Refractory Chronic Spontaneous Urticaria

Background:Omalizumab is an effective treatment for antihistamine-refractory chronic spontaneous urticaria (CSU), although treatment responses can vary significantly. While fast and slow responders are well-characterized, the profile of super-responders (SR) remains poorly understood. Objective: To identify clinical and laboratory predictors of SR and poor/non-response (PR) to omalizumab in refractory CSU. Methods: This retrospective study analyzed 307 CSU patients treated with omalizumab at a UCARE center between January 2023 and December 2024. SR was defined as achieving Urticaria Activity Score(UAS)=0 within 1 week and sustained control (UAS7≤6, UCT > 12); PR had the Urticaria Control Test (UCT)< 12 after three injections. Demographic, clinical, and laboratory parameters were compared. Results: SR patients (n=138) had lower rates of concomitant chronic inducible urticaria (CIndU) (26.8% vs. 48.5%, P<0.05), higher total Immunoglobulin E (IgE) (113.0 IU/mL), and elevated D-dimer. PR patients (n=35) were older (median 52.0 years), had higher angioedema rates (65.5%), lower atopy prevalence (47.1%), higher UAS7 scores, lower IgE (53.5 IU/mL), and higher autologous serum skin test(ASST) positivity (61.5%). Multivariate analysis identified male sex as protective for SR (OR = 0.556, P=0.025), while concomitant CIndU predicted non-SR (odds ratio, OR = 2.357, P=0.001). Predictors of PR included Body Mass Index (BMI) ≥28 kg/m² (OR = 5.147, P=0.023), angioedema (OR = 3.309, P=0.042), and ASST positivity (OR = 4.174, P=0.011); atopy was protective (OR = 0.299, P=0.025). Conclusion: Male sex and absence of CIndU predict super-response to omalizumab, while high BMI, angioedema, and ASST positivity predict poor response. Atopy is associated with better omalizumab response. These findings support personalized treatment strategies in refractory CSU, though further multiethnic validation is warranted.