Clinical difference between single subtype and mixed subtype chronic urticaria: A retrospective study

Background: The subtypes of chronic urticaria share a common clinical expression, but may show differences phenotypically. Meanwhile, two or more different subtypes of chronic urticaria can coexist in any given patient which may involve different phenotypes. Aims: The study aims to compare the two phenotypes in terms of demographics, clinical profile and treatment response. Methods: In this retrospective study, 2678 chronic urticaria patients were divided into the single subtype chronic urticaria group and mixed subtype chronic urticaria group as was appropriate.The differences in the clinical features, possible causes, urticaria activity score of seven days, dermatology life quality index score, laboratory investigations and response to treatments were evaluated among the two groups. Results: An obvious female predominance was detected in chronic urticaria, especially in mixed subtype chronic urticaria patients. Of the 2678 chronic urticaria patients, there were 837(31.25%) mixed subtype chronic urticaria. Chronic spontaneous urticaria combined with symptomatic dermographism was the most common group in the mixed subtype chronic urticaria. Patients with mixed subtype chronic urticaria were more likely to have associated chest tightness/shortness of breath and showed greater urticaria activity. In patients with single subtype chronic urticaria, the positive rate of family history with allergic rhinitis, asthma or urticaria was lower. Based on evaluation of the treatment, control with second-generation antihistamines at licensed doses was achieved in only 38.83% of mixed subtype chronic urticaria patients, compared with 56.32% of patients with single subtype. Limitations: First, this study was a single-center design retrospective study. Second, omalizumab treatment was not included. Third, the differences between different subtypes of mixed subtype chronic urticaria were not discussed in detail. Conclusion: This study showed that mixed subtype chronic urticaria had some distinct features. Comprehensive knowledge about it may help us define effective therapeutic strategies and improve symptom control and the quality of life for chronic urticaria patients.