Characteristics and Management of Patients With Severe Chronic Spontaneous and/or Inducible Urticaria Refractory to Optimized Omalizumab Treatment: A French Multicenter Observational Study.

The study is sponsored by the University Hospital of Besancon under the coordination of Dr. Julie Castagna from the Department of Dermatology and Allergology. Approximately ten percent of patients with severe chronic urticaria remain refractory to standard or optimized biologic therapy, and this observational multicenter retrospective project aims to thoroughly evaluate these challenging cases. By analyzing a target population of seventy adult participants across French hospitals, the research focuses on identifying specific clinical and biological traits, outlining risk factors associated with non-response to high-dose treatment regimens, and documenting the alternative therapeutic strategies that follow treatment failure. Data collection is structured retrospectively to cover the period from January 2020 through the end of December 2026, leveraging existing medical records without imposing any additional clinical visits or physical procedures on participants, aside from sending an informational mailer to ensure transparency regarding data utilization. Eligibility requires documented resistance to optimized omalizumab defined by a validated Urticaria Control Test score below six or less than fifty percent clinical improvement as judged by the investigator, alongside mandatory affiliation with the French social security scheme and a lack of objection from the participant regarding the secondary use of their personal health information. Strictly enforced exclusion conditions eliminate cases where omalizumab was initiated for alternative diagnoses, halted due to adverse side effects, or administered to vulnerable groups such as pregnant individuals, minors, or those under legal protection frameworks. To maintain absolute data integrity and regulatory compliance, individual participant data will not be shared publicly or externally because the documentation contains confidential and fully anonymized clinical details designed strictly to safeguard patient privacy throughout the research lifecycle.