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.
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. However, the level of ESR and CRP are inadequate in demonstrating disease activity and inflammation compared to other diseases. In this study, the investigators aimed to analyze and compare the systemic inflammatory index (SII), which is a hematologic parameter between subjects with radiographic axial spondyloarthritis, non-radiographic axial spondyloarthritis, and healthy controls. Secondarily, the relationship between disease activity and enthesitis score and SII scores in patients with radiographic and non-radiographic axial spondyloarthritis will be investigated.