Background: Little is known about alpha-gal (galactose-alpha-1,3-galactose) sensitization in patients with chronic urticaria (CU). The aim of this study was to examine the prevalence, predictors and clinical relevance of alpha-gal sensitization in patients with CU.

Methods: Two consecutive cohorts of newly referred patients with CU from a primary care allergology practice and a tertiary hospital dermatology department, plus a control group with allergic disease, but not CU, from the allergology practice, were interviewed and screened for alpha-gal sensitization (serum specific-IgE >= 0.35 KU/L).

Results: Of 733 patients included, 21 (5.6%) and 11 (3.9%) of CU patients from private practice and hospital, respectively, were alpha-gal sensitized. In total, 8 patients (38.1% of sensitized patients, and 2.1% of all CU patients) from private practice, and 2 patients (18.2% of sensitized patients, and 0.7% of all CU patients) from hospital, had clinically relevant alpha-gal allergy. In private practice, male sex (47.6 vs. 24.7%), p = 0.020, obesity (33.3 vs. 23.6%), p = 0.302, and frequency of angioedema (61.9 vs. 51.4%), p = 0.350; and in hospital, male sex (72.7 vs. 27.9%), p = 0.003, and high total immunoglobulin E (median 168 vs. 70.5 KU/L), p = 0.022 were associated with alpha-gal sensitization.

Conclusion: alpha-gal sensitization is observed in a small fraction of CU patients with only few patients experiencing clinically relevant sensitization. Certain patients, particularly from primary care, may constitute a relevant population for aimed testing.