Unveiling Treatment Response Predictors in Predominant Subtypes of Chronic Inducible Urticaria

Introduction: Chronic inducible urticaria (CIndU) is a subtype of chronic urticaria (CU), which requires specific triggers to occur. Despite their common occurrence, treatment response rates and predictors of treatment responses are largely lacking in the literature. This study evaluates antihistamine (AH) and omalizumab response rates in the most common CIndU subtypes and examines whether certain features can predict treatment responses. Methods: We retrospectively analyzed CU patients with at least one CIndU subtype and performed comparisons between subgroups, in a total of 423 patients (70% CIndU, 30% chronic spontaneous urticaria [CSU] plus CIndU). Results: The treatment response rates in CIndU were 51.6%, 51.5%, and 86.5% with standard-dose second-generation H1-antihistamines (sgAHs), updosed/ combined sgAH, and omalizumab, respectively. Overall AH response was higher in CIndU than CSU plus CIndU (78.3% vs. 62%, p = 0.002) and in symptomatic dermographism (SD) and cold urticaria (ColdU) than cholinergic urticaria (ChoU) (83.2% vs. 78.3 vs. 60.9%, p = 0.04). AH-refractory patients had a longer disease duration (45.2 ± 56.7 months vs. 37 ± 51.9 months, p = 0.04), more angioedema, accompanying CSU, mixed CIndU subtypes (37.5% vs. 21.1%, p = 0.003; 45.1% vs. 27.1%, p = 0.002; 8.8% vs. 2.4%, p = 0.014), and lower baseline urticaria control test scores (5.86 ± 3.3 vs. 8.6 ± 3.6, p < 0.001) than AH-responsive patients. Conclusion: CIndU exhibits a good response to both AHs and omalizumab. Notably, the response to AHs is more pronounced in SD and ColdU compared to ChoU. Disease duration, angioedema, accompanying CSU, mixed CIndU, and lower baseline UCT scores may be used to predict AH treatment outcome in CIndU.