The autologous serum skin test (ASST) predicts the response to anti-IgE treatment in Chronic Spontaneous Urticaria patients: a prospective study

Background.Chronic spontaneous ur�caria (CSU), characterized by recurrent itchy wheals and angioedema for > 6 weeks, is a quite common disease that may heavily impair the quality of life.Omalizumab, an an�-IgE mAb, has much improved the management of CSU but pa�ents' response to the drug may vary and predic�ve markers are s�ll largely missing.We inves�gated the predic�ve value of the autologous serum skin test (ASST) on omalizumab response.Methods: 15 pa�ents with severe CSU eligible for Omalizumab treatment were prospec�vely studied submi�ng them to ASST and to complete blood count, D-dimer, an�-thyroid peroxidase an�bodies, and total IgE measurement before the start of the treatment.Results.14/15 (93%) responded brilliantly to omalizumab at 3 months assessment.7 responded in less than 1 month ("early responders") and 7 only a�er mul�ple administra�ons ("late responders").Of 9 pa�ents scoring posi�ve on ASST, 7 (78%) were late, and 2 (22%) early responders to omalizumab (p= 0.021).Of 6 pa�ents scoring nega�ve on ASST, 5 were early omalizumab responders and 1 did not respond.The PPV and NPV of the ASST for a "late" response