Background: Chronic spontaneous urticaria (CSU) is a chronic, sometimes debilitating skin disorder characterized by the appearance of wheals, angioedema, or both for a period of more than 6 weeks. Many biomarkers were explored for severity evaluation such as d dimer and C Reactive Protein. Objectives: The aim of the current study is to assess the usefulness of peripheral eosinopenia as a valuable and an applicable biomarker for CSU severity. Patients and methods: A case control study was conducted on 60 CSU patients. Patients were divided into 30 patients with mild UAS7 score <15 representing the controls and 30 patients with severe UAS7 score >28 representing the cases. Eosinophils count and other variables were compared. Results: Severe cases demonstrated significantly higher age (median 34 vs. 29 years, P =0.043), CRP (14 vs. 2 mg/L, P <0.001) and positive ASST (56.7% vs. 23.3%, P =0.008). In contrast, severe cases demonstrated significantly lower eosinophilic count (median 21 vs. 123 cell/mm3, P <0.001), basophilic count (median 5 vs. 25 cell/mm3, P <0.001), and total IgE (median 93 vs. 221.5 IU/ml, P <0.001). The eosinophilic count showed a significant-excellent AUC of 0.954. The best cutoff point was ≤70, at which sensitivity and specificity were 96.7% and 86.7%, respectively.
Conclusion: Peripheral eosinophils are significantly lower count in severe urticarial patients (P value <0.001) and this could be used as a simple and accessible tool for monitoring urticaria activity.