Comparison of the characteristics of patients with chronic urticaria receiving standard- or high-dose omalizumab.

Summary: Background. In patients whose chronic urticaria (CU) cannot be controlled with omalizumab 300 mg and antihistamines, the dose can be increased up to 600 mg. The study aimed to compare the clinical characteristics of patients receiving 300 mg versus higher doses of omalizumab, and to evaluate baseline predictors for updosing. Methods. A total of 159 patients who have been followed up at a tertiary care allergy center and received omalizumab for at least 12 months were included. The clinical characteristics of those who received the standard-dose omalizumab (Group 1) were compared to the ones who received therapy over the standard dose (Group 2).  Results. A total of 139 (87%) were in Group 1, and 20 (13%) were in Group 2. CU duration at baseline was shorter in Group 2. Chronic inducible urticaria was present in 2%, and 40% of the patients in Group 1 and 2, respectively. Elevated D-dimer level was associated with high-dose omalizumab use (p < 0.001). Area under the curve in the ROC analysis was 0.812 and the cutoff value of D-dimer level was 0.46 mg/dl (p = 0.001, sensitivity and specificity 67%, and 84%, respectively). The anti-TPO positivity was higher in patients with low IgE (31% vs 8%, p = 0.008). Conclusions. Nearly one in every ten patients required higher doses of omalizumab therapy. D-dimer level seems to be a predictor for omalizumab updosing and unresponsiveness to standard dose. IgG-anti-TPO positivity and low IgE do not predict the need for dose escalation; however, this result should be strengthened with a larger number of patients.