Study subjects and conduct
The study was performed at the Center of Allergy and Immunology, City Clinical Hospital No. 52 of the Ministry of Healthcare of Moscow (Moscow, Russia) between May 2021 and February 2023 after approval by the independent local ethics committee (protocol #06/0621). All study participants provided prior written informed consent.
We analyzed 63 patients with expert-confirmed ColdU. Of these, 39 patients had typical ColdU confirmed by positive ICT and TempTest® CSTs. The other 24 patients had atypical ColdU with negative ICT and TempTest® CSTs. In both groups, we recorded gender, age, the incidence of life-threatening reactions like angioedema and hypotensive reactions (weakness, dizziness, loss of consciousness), comorbid CSU, and other types of CIndUs, frequency of allergic, autoimmune and oncological diseases, duration of ColdU, treatment, and results of standardized validated questionnaires (Urticaria Control Test, UCT; Dermatology Life Quality Index, DLQI). Patients with typical and atypical ColdU were similar in their demographic and clinical features, except for the duration of disease, which was 24 months (range 11 to 71 months) in typical ColdU and 212 months (range 60 to 360 months) in atypical ColdU (Table 1). We also investigated 15 healthy controls (HCs) who had no history of pathological reactions associated with cold exposure, and all of them had negative CSTs.