Résumé
Chronic Urticaria is characterized by the development of pruritic wheals, angioedema or both for more than six weeks. It may occur spontaneously (CSU) or be induced by environmental factors or physico-chemical stimuli (CIndU). Omalizumab is recommended as a third-line treatment following the use of second generation antihistamines, updosed if necessary in refractory CSU, and may be used off-label in CIndU. In up to 75% of cases, CSU and CIndU are associated, leading to a higher severity and a longer disease duration than isolated CSU. In this study, we aimed to characterize and evaluate the potential dissociation of response to Omalizumab in a population of patients with a combination of CSU and CIndU. Methods: we conducted a retrospective monocentric cohort study, in the Dermatology department of Montpellier University Hospital. We included patients with CSU associated with at least one form of CIndU, and treated with Omalizumab, from January 2017 to December 2022. Results: a total of 72 patients were included. The response to Omalizumab after six months of treatment was concordant between CSU and CIndU in 56.9% of patients. When concordant, the response was complete in 73.1% of these patients. Whenever the response was discordant, it was better for CSU than for CIndU in all patients but one. The total rate of complete response to Omalizumab after six months of treatment was 69.4% and 43.1% in CSU and CIndU, respectively. Discussion: in the literature, Omalizumab appears to be less effective in exclusive CIndU and in combined CSU and CIndU versus exclusive CSU. Our study showed a discordant response to Omalizumab in 43.1% of patients, almost always better in the CSU symptoms. The persistence of the CIndU symptoms in these patients appeared to impair their quality of life, although not significantly, compared to patients with a complete concordant response to treatment. Conclusion: a systematic identification of patients with a combination of CSU and CIndU using specific questionnaires and tests could lead to more appropriate therapeutic strategies and thus improve overall management in this population.