Validation of the Urticaria Activity Score for Cold Urticaria

Background: Cold urticaria (ColdU) is characterized by the appearance of wheals and/or angioedema and itch after exposure to cold stimuli. The Cold Urticaria Activity score (ColdUAS) is a newly devised patient-reported outcome measure (PROM) assessing disease activity in ColdU. Objectives: We aimed to validate the ColdUAS according to PROM guidelines, assess the optimal documentation period, and develop a scoring computation algorithm. Methods: We instructed 71 patients with typical and atypical ColdU to complete the ColdUAS questionnaire over 4 consecutive weeks and asked to fill out additional anchor instruments including global assessment tools and validated quality of life measures. The scoring computation for the ColdUAS was developed by an expert group and the questionnaire was tested for its construct, structural, convergent, and known-groups validity as well as for its reliability including internal consistency and test-retest reliability. Results: The ColdUAS is calculated from the first three questions in the ColdUAS questionnaire, and the optimal assessment period was 2 weeks. We developed a calculation sheet to facilitate its use. The score demonstrates robust construct, structural, and convergent validity, as well as validity among known groups. It exhibits high reliability, including internal consistency and test-retest reliability. Conclusions: The ColdUAS is a newly developed PROM to assess disease activity in adolescent and adult patients with typical or atypical ColdU, tailored to the specific symptoms of these patients. The validation study confirmed its validity and reliability as a valuable tool in routine care and clinical research.