Evaluation of the Systemic Immune-Inflammation Index and Systemic Inflammatory Response Index in Ankylosing Spondylitis Patients

Introduction: The aim of this study was to investigate the relationship between the Systemic Immune-Inflammation Index (SII) and Systemic Inflammation Response Index (SIRI) and disease activity in patients with ankylosing spondylitis (AS). Methods: In our study, 104 AS and 51 healthy controls (HC) were analyzed. The SII and SIRI differences between AS and HC were investigated. Those with BASDAI <4 were defined as remission (BASDAI-r) and those with BASDAI >4 as active (BASDAI-a). SII, SIRI, and other parameters were compared between the groups. As a second classification, patients were divided into two groups according to the Ankylosing Spondylitis Disease Activity Score (ASDAS) scores. Those with ASDAS <2.1 were defined as low-grade disease activity (ASDAS-l) and those with ASDAS >2.1 were defined as high-grade disease activity (ASDAS-h). SII, SIRI, and other parameters were compared between the groups. Results: The median SIRI value was significantly higher in the patient group than in the HC group. The mean SIRI value was significantly higher in the BASDAI-a group than in the BASDAI-r group and in the ASDAS-h group than in the ASDAS-l group, but the median SIRI levels did not differ significantly between the groups. The optimal cut-off value of SIRI for identifying active patients was 1.12. Conclusion: These results suggest that SIRI may be considered in the evaluation of patients with AS and may be a new biomarker to identify patients with active disease activity.