A prospective observational study correlating possible novel biomarkers with disease severity and antihistamine response in chronic spontaneous urticaria.

Background: Role of complement fraction 5a (C5a), interleukin (IL)-9, and apolipoprotein (apo) A-IV as biomarkers of disease severity and antihistamine response in chronic spontaneous urticaria (CSU) remains elusive.

Objective: To identify the role of C5a, IL-9, and apo A-IV as potential biomarkers in predicting disease severity and antihistamine response in CSU patients.

Methods: This was a prospective observational study of 95 patients and 42 controls. Serum analysis of C5a, IL-9, and apo A-IV was done using enyzme linked immunosorbent assay kits. Also, serum IgE and anti-thyroid peroxidase (TPO) levels were assessed in all patients. All patients were started on oral levocetirizine 5 mg at baseline and dose was titrated upwards to maximum of 20 mg based on response. Patients were categorized into antihistamine responders or nonresponders as per their disease response. Serological markers, serum IgE, and anti-TPO were correlated with baseline disease severity and antihistamine response.

Results: C5a levels were significantly higher in cases as compared to controls ( = 0.004). Significantly higher IL-9 levels were observed in antihistamine responders than nonresponders ( = 0.008). Baseline urticaria severity demonstrated a statistically significant positive and negative correlations with IL-9 ( = 0.277, = 0.007) and apo A-IV ( = -0.271, = 0.008) levels, respectively. Levels of serum IgE ( = 0.031) and anti-TPO ( = 0.039) were significantly higher in antihistamine nonresponders compared to responders.

Conclusions: IL-9 and apo A-IV might be potential novel biomarkers to predict urticaria severity. Higher IL-9 might be a predictor of antihistamine response. Elevated anti-TPO and serum IgE might predict poor antihistamine response.