Relationship Between Systemic Inflammatory Index and Disease Activity in Axial Spondyloarthritis

Axial spondyloarthritis is an inflammatory disease characterized by the involvement of the sacroiliac joints and the spine. Disease activity and structural changes are determined by using physical examination, imaging studies, laboratory parameters, and patient-reported indices. Among laboratory studies, Erythrocyte sedimentation rate (ESR) and c-reactive protein (CRP) are the most commonly utilized parameters. ESR and CRP are within the normal range in 40-50% of patients with spondyloarthritis and may remain within the normal range even during active disease. Therefore, the use of biomarkers suitable for the pathophysiology of the disease have been recommended. However, these tests are difficult to access and there is no consensus on showing disease activity. Systemic inflammatory index (SII) is a novel hematologic parameter and previous studies reported the relationship with disease activity in rheumatologic diseases, but the results are inconsistent.

This study will compare the SII between subjects with radiographic and non-radiographic axial spondyloarthritis with healthy subjects. Secondly, the study will investigate the relationship between SII, a new inflammation parameter, and disease activity in patients diagnosed with radiographic and non-radiographic axial spondyloarthritis.