Biomarkers of response to omalizumab in patients with chronic spontaneous urticaria.

Background and objectives: Managing chronic spontaneous urticaria (CSU) resistant to anti-histamines remains challenging, and predictors of omalizumab efficacy are not fully understood. This study evaluated omalizumab's effectiveness, response patterns, and predictors in CSU patients.

Materials and methods: A retrospective analysis was conducted on 72 patients receiving omalizumab for at least six months. Factors influencing response to anti-IgE therapy were examined.

Results: Among the 72 patients with chronic spontaneous urticaria (CSU), 86.1% responded to omalizumab: 58.3% had a good response (UAS-7 <6), 27.8% showed a partial response, and 13.9% were non-responders. Baseline total IgE levels were significantly higher in responders compared to non-responders (good: 291.4 kUA/L vs. 60.2 kUA/L, p = 0.003; partial: 148 kUA/L vs. 60.2 kUA/L, p = 0.049). ROC analysis identified a total IgE cut-off of 64 kUA/L for predicting omalizumab response (AUC: 0.67, p = 0.019; sensitivity: 82%, specificity: 48%). Non-responders had significantly higher erythrocyte sedimentation rates (20.0 mm/h vs. 8.25 mm/h, p = 0.018). Patients with recurrence post-treatment had elevated thyroid-stimulating hormone (TSH) and C-reactive protein (CRP) levels (p = 0.006, p = 0.007). Among responders, 29% had an early response and 71% a late response. Early responders had significantly lower anti-thyroglobulin (anti-TG) and antinuclear antibody (ANA) positivity (p = 0.036, p = 0.035). Systemic inflammatory indices (SII, SIRI) did not predict response.

Conclusions: Baseline total IgE may predict omalizumab response, while ANA and anti-TG positivity correlate with delayed response. Elevated TSH and CRP levels may indicate a higher recurrence risk after treatment discontinuation.