Comorbid Inducible Urticaria Is Linked to Non-Autoimmune Chronic Spontaneous Urticaria: CURE Insights

Background: Patients with chronic spontaneous urticaria (CSU) can have comorbid inducible urticaria (CIndU). How comorbid CIndU affects patients and their CSU is largely unclear. Objective: To compare patients with CSU with and without comorbid CIndUs for differences in demographic features, clinical characteristics, and laboratory markers. Methods: We analyzed 708 patients with CSU of our Urticaria Center of Reference and Excellence enrolled in CURE, the chronic urticaria registry. CURE data collected until October 2022 were used to compare patients with and without comorbid CIndU for their demographic characteristics, disease onset, activity, impact, and control, as well as concomitant allergic and autoimmune diseases and laboratory parameters associated with autoimmune CSU. Results: Of 708 patients with CSU, 247 (35%) had comorbid CIndU. Compared with patients with standalone CSU, patients with CSU with comorbid CIndU were significantly younger, had earlier disease onset, longer disease duration, higher impact on quality of life, and a higher rate of concomitant allergic diseases. Moreover, patients with CSU with comorbid CIndU less often had features linked to autoimmune CSU such as angioedema, concomitant autoimmune diseases, eosinopenia, low levels of total IgE, and low total IgE combined with elevated anti-thyroid peroxidase IgG. Conclusions: Autoimmune CSU may be less common in patients with comorbid CIndU than without, and comorbid CIndU may point to autoallergic CSU.