Enrolment and Questionnaires
Children presenting with CU were consecutively recruited from 2013 to 2021 as part of our CU registry at the Montreal Children’s Hospital and an affiliated pediatric allergy clinic. Written informed consent was obtained from the parents and/or legal guardians of study participants, and an assent form was obtained from children seven years and older. This registry was approved by the Centre for Applied Ethics from the McGill University Health Centre Research Ethics Board (REB 12-255 GEN, June 3, 2013). ColdU was diagnosed based on clinical history and wheal formation after five minutes of skin exposure to a plastic bag-wrapped ice cube5. The diagnosis of coldU also included cases with cold-induced symptoms (at least two episodes in history) in the absence of reaction to the ice cube test (atypical coldU). Patients were also assessed at study entry for concomitant CIndUs by clinical history and/or provocation testing, as well as for concomitant CSU. Data on coldU triggers were extracted from the patients’ medical charts.
At study entry, we administered a standardized questionnaire querying on the patient’s demographics, symptoms, comorbidities, family history, and management of their coldU. Beginning in 2018, participants completed the Urticaria Control Test (UCT) at study entry. Patients recruited prior to 2018, whose urticaria had not resolved, completed the UCT at follow-up. Children less than 12 years of age were permitted to complete the questionnaire and UCT with the help of their guardians, a score of at least 12 was considered well-controlled8.