Abstract: 【Abstract】 Objective To investigate the efficacy and safety of omalizumab in the treatment of chronic urticaria （CU） patients with poor response to H1 antihistamines. Methods CU patients, who showed poor response to H1 antihistamines and received omalizumab treatment, were collected from the Department of Dermatology, Xiangya Hospital, Central South University from June 2020 to June 2021. The efficacy of omalizumab was evaluated by using the 7-day urticaria activity score （UAS7） and urticaria control test （UCT） score at weeks 4, 12 and 24 after the start of treatment. The t-test, chi-square test, and Pearson correlation analysis were used to analyze the relationship between the clinical characteristics and efficacy. Results A total of 121 CU patients who met the inclusion criteria and had relatively complete medical records were included in this study, including 54 males （44.63%） and 67 females （55.37%）, and their ages ranged from 13 to 70 years （39.88 ± 14.36 years）; 88 patients were diagnosed with chronic spontaneous urticaria （72.73%）, 10 with chronic inducible urticaria （8.26%）, and 23 with chronic spontaneous urticaria accompanied by chronic inducible urticaria （19.01%）. At week 4 after the start of omalizumab treatment, the response rate was 50.86% （59/116）, and the complete response rate was 25.86% （30/116）; at week 12, the response rate was 78.26% （54/69）, and the complete response rate was 34.78% （24/69）; at week 24, the response rate was 64.71% （22/34）, and the complete response rate was 23.53% （8/34）. At week 4, CU patients with baseline serum total IgE levels of < 40 IU/ml had a lower response rate （26 cases, 30.77%） than those with baseline serum total IgE levels of ≥ 40 IU/ml （61 cases, 65.57%; χ2 = 8.93, P = 0.004）. Correlation analysis showed that the age at treatment, age at onset, allergic diseases, concomitant symptoms, baseline erythrocyte sedimentation rates, and baseline C-reactive protein levels were significantly correlated with the UCT scores （all P < 0.05）, while the course of disease, clinical types, serum total IgE levels, peripheral blood counts, dermatology life quality index scores, and UAS7 scores were not significantly correlated with the UCT scores. Among the 121 CU patients, 8 （6.61%） reported mild to moderate adverse reactions. Conclusion Omalizumab could effectively improve clinical symptoms and signs of CU patients with poor response to H1 antihistamines, and was well tolerated;omalizumab treatment may be more beneficial to patients without allergic comorbidities such as allergic rhinitis, without concomitant symptoms such as angioedema, and with lower erythrocyte sedimentation rates and C-reactive protein levels.

Key words: Urticaria, Biological agents, Treatment outcome, Chronic spontaneous urticaria, Omalizumab