Concomitant Chronic Urticaria in Children: A Distinct Severe Phenotype.

Introduction: Chronic spontaneous urticaria (CSU) presents as repetitive spontaneous hives and/or angioedema lasting for at least 6 weeks. In contrast, chronic inducible urticaria (CIndU) is triggered by specific stimuli. This study aimed to characterize children who have concurrent CSU and CIndU excluding children with symptomatic dermographism and to identify factors that distinguish them from children with CSU alone or CIndU alone.

Methods: This prospective cohort study was conducted over an 11-year period, from 2013 to 2024, at Montreal Children's Hospital in Canada. It included pediatric patients aged 0-18 years with chronic urticaria.

Results: During the study period, 202 pediatric patients with chronic urticaria were included. Of these, 20 patients (9.9%) had both CSU and CIndU concomitantly. Cold urticaria was the most common CIndU associated with concomitant urticaria group, affecting 9 patients (45%). The mean age of patients with concomitant urticaria was 6.2 years (IQR: 5.0-11.8), and the majority were females (60%). Eight patients (42%) initially presented with CSU alone. Uncontrolled CSU (baseline UAS7 scores ≥16) was more common in patients with concomitant urticaria (60%) versus those with isolated CSU (27.5%) or CIndU (17.2%) (p < 0.01). Omalizumab usage was significantly higher in children with concurrent CSU and CIndU (20%) compared to those with CSU alone (5.9%) or CINDU alone (0%) (p = 0.04 and 0.01, respectively).

Conclusion: Pediatric patients who have concomitant CSU and CIndU represent a more severe CU phenotype that requires the use of biologics like omalizumab as compared to children with CSU/CIndU alone.