High‐dose non‐sedating antihistamines are used insufficiently in chronic urticaria patients treated with omalizumab

BACKGROUND: The lifetime prevalence of chronic urticaria (CU) is 0.5%–1%. In some patients with CU, symptomatic control is not achieved with non‐sedating second‐generation H1 antihistamines (nsAH1) alone, even with quadrupled standard doses as recommended in international guidelines. In these cases, biological treatment with omalizumab can be added. Since omalizumab is expensive compared to antihistamines, lack of adherence to guidelines for high dose nsAH1 (up to four‐fold standard dose per day) may be associated with substantial unnecessary costs. The aim was to measure the use nsAH1 before and during omalizumab use for the first time in an omalizumab treated CU population. METHODS: We identified all Danish patients with CU who initiated omalizumab from March 2014 to December 2018 and evaluated new and ongoing nsAH1 treatments using the Danish nationwide registries. RESULTS: A total of 955 CU patients initiated treatment with omalizumab within the study period (median age 40 years [IQR 28–50], 74.5% females). During the 12 months prior to omalizumab initiation, 95.6% of the patients filled at least one prescription with nsAH1 at some point, while 84.7% filled at least one prescription during the three months before omalizumab. From 3 months before omalizumab initiation till 3 months after, the proportions of users of high‐dose nsAH1 was maximum 31.1%. CONCLUSIONS: Omalizumab was usually administered before sufficient nsAH1 treatment was tried. In despite of the labelling that omalizumab should be co‐administered with high dose nsAH1, this does not happen This may lead to substantial unnecessary costs.