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Background: Omalizumab resistance (OmR) in chronic spontaneous urticaria (CSU) remains poorly understood. Objective: To identify clinical and laboratory attributes of patients that may be predictive of OmR in CSU. Methods: We conducted a retrospective observational study by using an electronic patient record data base of patients with severe CSU refractory to a fourfold H1-antihistamine dose, treated with omalizumab 300 mg every 4 weeks for at least 24 weeks. Complete response (CR) was defined as the reduction of baseline urticaria activity score by ≥ 90%, partial response (PR) by ≥ 30% to Results: Sixty-three patients (58.9%) had a complete remission at 24 weeks of omalizumab therapy, and 16 patients (14.9%) had OmR. The patients who were OmR were characterized by a higher rate of arterial hypertension 7 (43.8%), higher mean ± standard deviation (SD) high-sensitivity C-reactive protein (hs-CRP) level (10.3 ± 8.2 mg/L), mean ± SD white blood cell (WBC) count (9.1 ± 2.8 × 10³ cells/mL), and higher mean ± SD C3 level (164.3 ± 45.4 mg/dL) at baseline than the patients with CR (arterial hypertension, 9 13.1%, p = 0.009; mean ± SD hs-CRP, 3.4 ± 10.1, p = 0.014; mean ± SD WBC count, 6.5 ± 3.8 × 10³ cells/mL, p = 0.012; and mean ± SD C3 level, 121.8 ± 42.1 m/dL, p 3.0 mg/L (odds ratio 1.94 95% confidence interval, 1.28-3.15, p = 0.009) and with C3 > 160 mg/dL (odds ratio 1.54 95% confidence interval, 1.05-2.36, p = .017). Conclusion: Obesity, arterial hypertension, high plasma C3 level, and high-CRP level were associated with OmR in severe CSU.
Magen et al. (Mon,) studied this question.