Omalizumab in Chronic Spontaneous Urticaria: Assessment of Response in Twenty-Five Patients

Background Omalizumab is a recombinant humanized monoclonal antibody against immunoglobulin E (IgE). It is approved for the treatment of chronic spontaneous urticaria (CSU) in patients ≥12-years of age. Objective We carried out a retrospective cross-sectional study in 25 patients with CSU to evaluate the characteristics of response of CSU to omalizumab treatment. Method A retrospective cross-sectional study of a convenient sample of all patients diagnosed as CSU who have been using omalizumab treatment during the study period from January 2018 to January 2020 in the Dermatology Department in King Abdulaziz Hospital, Makkah, Saudi Arabia. Results A total of 25 patients have participated in this study. The average age of patients was 40-years. Majority of the patients were female (52.0%, n=15). The average duration of illness was 1.32-years. Majority of the patients (72.0%, n=18) received two courses of omalizumab treatment. Minority of patients (28.0%, n=7) received one course of omalizumab treatment which was statistically significant (p value<0.01). Number of patients who have been using oral 2nd generation antihistamine during the first course and 2nd course was (72%, n=18 out of 25) and (50%, n=9 out of 18) respectively. Number of flare-ups during 2nd course (1.72 flares up per patient, n=31 flare-ups among 18 patients) was less than the number of flares-up during 1st course (2.96 flares-up per patient, n=74 flare-ups among 25 patients) which was statistically significant (p value<0.01). Number of patients who showed no flare-ups during the 1st and 2nd course of omalizumab treatment was (16%, n=4 out of 25 patients) and (27.77%, n=5 out of 18 patients) respectively. The average intensity of flares-up during 2nd course of omalizumab treatment was less than the average intensity of flares-up during first course of omalizumab treatment as the following; during 2nd course ( 33.33%, n=6 out of 18 patients), (27.77% n=5 out of 18 patients), (11.11%, n=2 out of 18 patients) mild, moderate and severe flares-up respectively and the severity during 1st course was (40.0%, n=10 out of 25 patients), (28.0%, n=7 out of 25 patients), (16.0%, n=4 out of 25 patients) mild, moderate and severe flares-up respectively. Conclusion According to expert’s guidelines, CSU of ≥3-years would be treated with omalizumab for a minimum of one-year. In our study, in spite of the short duration of CSU (average duration was 1.32-years), the majority of patients (72.0%, n=18) received omalizumab for 1-year (two courses of omalizumab treatment) suggesting that the majority of patients with CSU in general requires omalizumab ≥1-year. Our study also showed 5 patients who were free of any flare-up and they were not using 2nd generation antihistamines suggesting that omalizumab alone as monotherapy can be effective