Abstract: 【Abstract】 Objective To evaluate the efficacy of omalizumab in the treatment of chronic spontaneous urticaria （CSU）, and to analyze its influencing factors. Methods CSU patients treated with omalizumab were prospectively enrolled from the Department of Dermatology, General Hospital of Ningxia Medical University from October 2021 to October 2023. These patients received subcutaneous injections of omalizumab at a dose of 300 mg every 4 weeks （150 mg for patients aged under 12 years） for at least 3 consecutive sessions. Data on general information, blood routine test, and serum total IgE levels were collected, and the 7-day Urticaria Activity Score （UAS7）, Urticaria Control Test （UCT）, Dermatology Life Quality Index （DLQI）, Chronic Urticaria Quality of Life Questionnaire （CU-Q2oL）, and the Beck Anxiety Inventory （BAI） were evaluated by dermatologists at baseline, and after 4, 8, and 12 weeks of treatment. A decrease in UAS7 score of ≥ 11 points was defined as good disease control, while a decrease in UAS7 score of < 11 points was defined as poor control. Univariate binary logistic regression and multivariate logistic regression models were used to identify factors influencing the efficacy. Results A total of 81 CSU patients were enrolled, including 34 males （42.0%） and 47 females （58.0%）; their ages ranged from 6 to 66 years （39.2 ± 17.9 years）, and the disease duration was 42.3 ± 6.9 months; the serum total IgE levels were 249.5 ± 216.3 IU/ml, with 54 patients （66.7%） showing elevated IgE levels （> 100 IU/ml）. Compared with baseline levels, the UAS7, DLQI, and CU-Q2oL scores all significantly decreased at weeks 4, 8, and 12, while the UCT scores significantly increased （all P < 0.05）. According to the UAS7 change values, 68 patients （83.9%） were well controlled, and 13 （16.1%） were poorly controlled. Univariate logistic regression analysis showed that higher total IgE levels and higher mean platelet volume （MPV） were associated with better efficacy, while higher body mass index （BMI）, higher BAI, and the complication of other allergic diseases were associated with poorer efficacy （all P < 0.05）. Multivariate logistic regression analysis indicated that BMI, BAI, and MPV significantly affected efficacy: higher MPV was associated with better efficacy （OR = 3.36, 95% CI: 1.196 - 9.465, P = 0.020）, while higher BMI （OR = 0.76, 95% CI: 0.599 - 0.957, P = 0.016） and higher BAI （OR = 0.92, 95% CI: 0.870 - 0.985, P = 0.021） were associated with poorer efficacy. During the whole study, only 4 patients （5%） experienced drowsiness, low fever, redness or discomfort at the injection sites, and no serious adverse events were reported. Conclusion Omalizumab exhibited significant efficacy and high safety in the 12-week treatment of CSU, and BMI and BAI appeared to be risk factors for efficacy, while MPV seemed to be a protective factor affecting efficacy.

Key words: Chronic urticaria, Omalizumab, Root cause analysis, Clinical efficacy, Safety