Abstract: 【Abstract】 Objective To retrospectively evaluate efficacy and safety of omalizumab in the treatment of chronic spontaneous urticaria（CSU）, as well as recurrence after its withdrawal. Methods Clinical data on patients with CSU, who received omalizumab treatment in Peking University First Hospital from February 2018 to January 2021, were collected and analyzed retrospectively. Through outpatient follow-up, urticaria control test （UCT） and dermatology life quality index （DLQI） were recorded to assess disease severity, and adverse events and recurrence after omalizumab withdrawal were monitored. Comparisons of normally distributed measurement data between groups were carried out using t test or analysis of variance, comparisons of non-normally distributed measurement data between groups using Mann-Whitney U test, Wilcoxon signed-rank test or Kruskal-Wallis H test, and comparisons of enumeration data between groups using chi-square test or Fisher′s exact test. Results A total of 59 patients with CSU were included and treated with omalizumab for at least 3 months, of whom, 45 were treated for more than 6 months, and 15 for more than 12 months. After the start of omalizumab treatment, UCT scores increased from 3.0 （1.0, 6.0） points at baseline to 11.0 （3.0, 14.0） points at 1 month and 15.0 （12.0, 16.0） points at 3 months （both P < 0.05）; DLQI scores decreased from 16.0 （12.0, 20.0） points at baseline to 7.0 （1.0, 13.0） points at 1 month and 1.0 （0.0, 4.0） points at 3 months （both P < 0.05）. The proportion of patients achieving partial or complete disease control increased from 0 at baseline to 44.1% at 1 month, 78.0% at 3 months, and 88.9% at 6 months. The proportion of patients whose quality of life was severely or extremely severely affected by CSU decreased from 84.7% at baseline to 30.5% at 1 month, 15.3% at 3 months, and 4.4% at 6 months. The disease duration was significantly shorter in the complete response group and partial response group than in the non-response group （t = -2.894, -2.511, P = 0.011, 0.036, respectively）; the treatment duration was significantly longer in the complete response group than in the partial response group and non-response group （t = 2.479, 2.677, P = 0.039, 0.022, respectively）. Compared with the rapid response group, the slow response group showed higher DLQI scores （Z =－2.622, P = 0.009） and lower UCT scores （Z =－2.746, P = 0.006） at baseline. Nineteen patients withdrew omalizumab after complete control of CSU, of whom 13 （68.4%） experienced relapse 7.0 （5.0, 8.0） weeks after the withdrawal, and showed significantly higher UCT scores at relapse than at baseline （Z = 3.172, P = 0.001）. The disease duration was significantly longer in the recurrence group than in the non-recurrence group （Z =－2.635, P = 0.007）. After recurrence, 5 patients restarted omalizumab treatment, and all of them regained partial or complete disease control. The adverse events reported during the treatment were all mild to moderate. Conclusions Omalizumab can effectively and safely control symptoms of CSU and improve the quality of life of patients with CSU. However, recurrence frequently occurs after omalizumab withdrawal, and reinitiating omalizumab treatment after recurrence is still effective.

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