LAUSR

Introduction: Chronic urticaria (CU) is a condition usually lasting longer than 6 weeks, with wheals and angioedema, sometimes both. Omalizumab is a recombinant humanized monoclonal IgG antibody developed against IgE. In some patients with CU, treatment response to omalizumab is good, but in some patients, it is poor. We aimed to compare the clinical features and laboratory parameters of the patients who responded and did not respond to omalizumab treatment among patients diagnosed with CU. Methods: Patients treated with omalizumab for the diagnosis of CU were evaluated retrospectively. Treatment response to omalizumab was evaluated by urticaria control test (UCT) (responder to omalizumab: UCT score ≥12 at 6 months and an increase of ≥3 compared to baseline). The clinical features and laboratory parameters of the patients who responded and did not respond to treatment were compared. Results: The mean age of the 220 patients, 66 (30%) men and 154 (70%) women, who received 300 mg of sc omalizumab every 4 weeks for CU was 38.89 ± 12.76 years. One hundred eighty-nine (85.9%) patients had good response to omalizumab treatment at the end of 6 months. Atopy (n = 73 [38.6%], p = 0.026), eosinophil count (median = 190 [0–800] [cells/µL], p < 0.001), basophil count (median = 40 [0–100] [cells/µL], p = 0.021), and total IgE (median = 240.5 [45–2,644] [kU/L], p < 0.001) level were significantly higher in the omalizumab responder patients (UCT score ≥12 at 6 months and an increase of ≥3 compared to baseline). Psychiatric disorders (n = 13 [41.9%], p = 0.008) and anti-TG (n = 11 [35.5%] [>2 IU/mL positive], p = 0.024) were significantly higher in the omalizumab nonresponder patients (UCT score ≤11 at 6 months). A weak but significant clinical correlation was found between blood eosinophil count (r = 0.168, p = 0.013), blood lymphocyte count (r = −0.149, p = 0.027), total IgE level (r = 0.207, p = 0.002), and increase in UCT score. As a result of the ROC curve analysis, the blood eosinophil count (AUC: 0.763, p < 0.001), total IgE level (AUC: 0.866, p < 0.001), and blood basophil count (AUC: 0.662, p = 0.004) had diagnostic value in predicting the response to omalizumab treatment in patients with CU. Conclusion: The patients with CU who were atopic with high eosinophils, high basophils, and high total IgE levels had good response to omalizumab treatment, but the patients with concomitant psychiatric disease and positive thyroid autoantibodies had poor response to omalizumab treatment. These findings obtained in our study should be tested in randomized controlled studies.