Omalizumab in severe chronic urticaria: are slow and non-responders different?

The response to Omalizumab by patients with severe Chronic Spontaneous Urticaria (CSU), may be rapid, slow, or absent. An early response has been associated with an IgE-mediated auto-allergic pathogenic mechanism, whereas little is known about slow and non-responders. To compare CSU patients responding slowly or non-responding to Omalizumab. Forty-six patients showing a slow (n= 23) or absent (n= 23) response to Omalizumab out of a cohort of 170 patients with severe CSU (UAS-7 major 30) were studied. Several baseline clinical and serological parameters were compared in the two groups. Apart from a lower prevalence of atopic diseases (p minor 0.05) and a slightly higher prevalence of thyroid autoimmunity in non-responders, the two groups were similar in terms of clinical and serological features. The majority of patients in both groups showed low baseline total IgE levels. Patients with severe CSU showing a slow response or not responding at all to omalizumab show impressive similarities. It is currently not possible to predict whether patients with severe CSU and low IgE levels will show a slow response or will not respond to anti-IgE treatment.