Study Suggests SII, SIRI Effective in Determining Omalizumab Tolerance in CSU

A new investigation from Turkey suggested that the systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI) could be used to effectively predict the response to omalizumab treatment in patients with chronic spontaneous urticaria (CSU), though more comprehensive studies to confirm this relationship were suggested.

Chronic spontaneous urticaria is assumed to affect roughly 1-2% of the population, and various inflammatory markers have been associated with the prognosis of the disease.

Recent research has suggested that omalizumab could be used to treat CSU. But the mechanism of action for the treatment has not been fully elucidated in patients with CSU. Likewise, the relationship between CSU and SII and SIRI has also not been studied.

As such, investigators led by Nur Cohan Cosansu, MD,Department of Dermatology at Sakarya University, evaluated the effectiveness of these parameters in patients with CSU, as well as if they could be used to predict a patient’s response to omalizumab.

Between 2017 and 2021, Cosansu and colleagues enrolled 124 patients with CSU from Sakarya University, all of whom received omalizumab treatment. Of these patients, 84 were female and 40 were male. The mean age of eligible patients was 43.9 years.

Any patients who did not respond to high-dose H1-antihistamine therapy such as rupdatadine or fexofenadine were treated with a 300 mg dose of omalizumab every 4 weeks.

Patients were deemed eligible based on a screening of their medical records, and those with inflammatory, autoimmune, or active infectious diseases, malignancy, or pregnancy were excluded.

C-reactive protein (CRP), urticaria activity score-7 (UAS-7), neutrophil count, lymphocyte count, monocyte count, eosinophil count, and platelet count were recorded before and after 12 weeks of omalizumab treatment in all eligible participants, and the activity of CSU was assessed from UAS-7.

Patients were considered non-responders if the UAS-7 score was ˃6.

In total, 53.2% of patients with CSU had a good response to omalizumab in 3 months od treatment, with the percentage increasing to 75.8% following 6 months of treatment.

Notably, a significant decrease in SII, SIRI, CRP, and UAS-7 was observed in the third month of omalizumab treatment, and the responder groups at 3 and 6 months of treatment had significantly higher baseline SII and SIRI levels than non-responders (P<.001).

Despite this, no difference in CRP and UAS-7 levels between responders and non-responders were observed (P<.001).

Additionally, multivariate logistic regression analysis revealed that pre-treatment SII (P=.036) and SIRI (P=.002) were found as independent predictors of responders to omalizumab treatment.

To their knowledge, Consansu and colleagues were the first to analyze the relationship between CSU and SII and SIRI, which indicated that CRP, UAS-7, SII, and SIRI decreased in patients withCSU afteromalizumabtreatment.

“Moreover, SII and SIRI appear to bea cost-effective,convenient, noninvasive, and reproducible biomarkers for treatment response in patients with CSU treated with omalizumab,” the team wrote. “Further studies comprising a greater number of patients are required to validate the findings and identify the underlying mechanisms.”

The study, "New markers to predict the response to omalizumab in chronic spontaneous urticaria," was published online in Dermatologic Therapy.