Is it possible to use complete blood collection based systemic inflammatory indices as potential biomarkers for chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is mediated not only by mast cells but also by eosinophils and basophils. We evaluated whether complete blood collection based systemic inflammatory indices- including the systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), aggregate Index of Systemic Inflammation (AISI), systemic inflammation modulation index (SIMI), neutrophil-to-lymphocyte ratio (NLR), eosinophil-to-lymphocyte ratio (ELR), platelet-to-lymphocyte ratio (PLR), basophil-to-lymphocyte ratio (BLR)-and platelet parameters (mean platelet volume [MPV], platelet distribution width [PDW], platelet large cell ratio [PLCR]) reflect CSU severity or treatment response. A retrospective study of 190 CSU patients and 570 matched controls was performed, with sensitivity analyses using propensity-score matching (PSM) and inverse-probability-of-treatment weighting (IPTW). Subgroup analyses examined UAS7, antihistamine response and allergy history. As a result, CSU patients exhibited lower SII/SIRI, white blood cells (WBC), neutrophils, lymphocytes, and NLR, alongside higher MPV/PLCR and reduced PDW. NLR showed a weak correlation with UAS7, and systemic indices did not reliably differentiate standard-dosed and updosed antihistamine response. Patients with allergy history demonstrated lower eosinophils and ELR. CSU is characterized by reduced systemic inflammatory indices and enhanced platelet activation. Among these, NLR may serve as a cost-effective supplementary tool for assessing systemic inflammation trends of CSU.