Abstract
Introduction
Chronic spontaneous urticaria (CSU) is a debilitating inflammatory skin disease characterized by recurrent wheals, angioedema, or both without an identifiable trigger. Omalizumab is an effective treatment for antihistamine-refractory CSU; however, treatment response varies among patients. Baseline serum immunoglobulin E (IgE) and eosinophil levels have been proposed as potential biomarkers of treatment response. This systematic review evaluated the association between baseline serum IgE and eosinophil levels and response to omalizumab in patients with CSU.
Main Body
A systematic review was conducted using PubMed, Web of Science, Cochrane Library, and Google Scholar. Following duplicate removal, 606 unique records underwent title and abstract screening. 48 full-text articles were assessed for eligibility, and 10 studies met inclusion criteria for qualitative synthesis. Studies with extractable responder versus non-responder data using validated clinical response measures were included in the primary meta-analysis. Pooled mean differences (MD) with 95% confidence intervals (CI) were calculated, and heterogeneity was assessed using I².
Of the 10 studies included in the systematic review, two met criteria for the primary quantitative synthesis of baseline IgE and eosinophil levels. Responders demonstrated significantly higher baseline serum IgE concentrations than non-responders (MD +109.1 IU/mL, 95% CI 54.1–164.2; I² = 0%; p 0.001). In contrast, baseline eosinophil counts were not significantly different between responders and non-responders (MD −14.1 cells/µL, 95% CI −98.1 to 69.8; I² = 44%; p = 0.74). Sensitivity analyses incorporating studies with less comparable response definitions attenuated the association between IgE and treatment response (MD +79.6 IU/mL, 95% CI −4.4 to 163.6; I² = 51%; p = 0.063), while eosinophil results remained nonsignificant (MD −21.2 cells/µL, 95% CI −53.0 to 10.6; I² = 0%; p = 0.19). The remaining eligible studies were included in the qualitative synthesis because they lacked comparable quantitative data for meta-analysis.
Conclusion
Higher baseline serum IgE appears to be associated with improved response to omalizumab in CSU when analyses are restricted to studies with comparable responder definitions, whereas baseline eosinophil counts were not predictive of treatment response. The limited number of studies eligible for quantitative synthesis highlights an important evidence gap and underscores the need for standardized outcome reporting in future studies.