Current Treatment Practices and Efficacy in Solar Urticaria: Insights from a Patient Survey

Lea Alice Kiefer^1,2*Felix Aulenbacher^1,2Dorothea Terhorst-Molawi^1,2Ana Maria Giménez-Arnau³Margarida Gonçalo⁴Atsushi Fukunaga⁵Emek Kocatürk^1,2,6Kanokvalai Kulthanan⁷Sheila McSweeney⁸Heike Rockmann⁹Karsten Weller^1,2Lesley E Rhodes¹⁰Manuel Pedro Pereira^1,2

• ¹Institute of Allergology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
• ²Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Immunology and Allergology, Berlin, Germany
• ³Department of Dermatology, Hospital del Mar-Institut d’Investigacions Mèdiques Universitat Pompeu Fabra de Barcelona, Barcelona, Spain
• ⁴Department of Dermatology, University Hospital, Coimbra Local Health and Faculty of Medicine, University of Coimbra, Coimbra, Portugal
• ⁵Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, Kobe, Japan
• ⁶Department of Dermatology, Koç University School of Medicine, Istanbul, Türkiye
• ⁷Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bankkok, Thailand
• ⁸St. John's Institute of Dermatology, Guy's Hospital, London, United Kingdom
• ⁹Department of Dermatology/Allergology, University Medical Centre Utrecht, Utrecht, Netherlands
• ¹⁰Faculty of Biology, Medicine and Health, University of Manchester, and Dermatology Centre, Salford Royal Hospital, NCA NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom

Background: Solar Urticaria (SolU) is a rare chronic inducible urticaria and photodermatosis, presenting with wheal/flare formation accompanied by severe itch, following exposure to light in the triggering action spectrum. Therapeutic options remain limited for SolU and the perspective of patients regarding the efficacy of available treatments remains unknown. Methods: Patients with SolU, organized in a disease specific facebook group, were asked to complete an electronic questionnaire on their condition and therapies performed between May 2023 and April 2024. The certainty of SolU diagnosis was differentiated as (i) physician confirmed by clinical presentation, (ii) light provocation tests or (iii) patient-reported. Study outcomes included clinical presentation, triggering action spectrum, disease severity, impairment of quality of life, therapies performed and their efficacy. Logistic regression models were used to study the association between clinical factors and treatment outcomes. Results: A total of 112 patients (females: n=94, median age: 42 years) participated in the study. Most patients considered their condition severe or extremely severe (n=72, 76.6%) with a very/extremely impacted quality of life (n=82, 86.3%). The majority of patients received non-sedating antihistamines (58.9%. n=66), leading to worsening, no change or only slight improvement in most cases (82.2%, n=53). Omalizumab was given to 28 patients and induced complete control in 32.1% of cases. Treatments with sedating antihistamines, ciclosporin, systemic corticosteroids, phototherapy and polypodium leucotomas were performed in a residual number of patients and did not lead to a substantial improvement of the symptoms. Antihistamines were more effective in patients with mild disease, whereas omalizumab maintained a positive response across different disease severity levels. Conclusion: SolU is generally perceived as severe by affected patients, leading to a high impairment of quality of life. Performed therapies including off-label treatments are not sufficient to reach complete remission of symptoms in the majority of patients. Effective therapeutics for SolU are urgently needed to achieve a better care of this highly burdened patient population.