New Inflammatory Marker Associated with Disease Activity in Rheumatoid Arthritis: The Systemic Immune-Inflammation Index.

This study aimed to discover a new index for disease activity by reviewing the relationship between the Systemic Immune-Inflammation Index and Systemic Inflammation Response Index in rheumatoid arthritis.A total of 109 patients with rheumatoid arthritis and 31 healthy controls were involved in the study. Based on disease activity score (DAS-28) calculated by the erythrocyte sedimentation rate, rheumatoid arthritis patients were divided into two groups: Group 1 comprised patients in remission (DAS-28<2.6); Group 2 was the active patient group (DAS-28>2.6). The Systemic Immune Inflammation Index and the Systemic Inflammation Response Index compared between the groups.The Systemic Immune-Inflammation Index is 666.415±33.00 in the patient group and 596.71±57.64 in the control group, and the difference between the groups is statistically significant (p=0.002). The Systemic Immune-Inflammation Index was 574.69±34.72 in group 1 and 702.25±39.56 in group 2. There was a significant statistical difference between the active and remission patients (p=0.030). The Systemic Inflammation Response Index was not statistically significant between the groups. Different cut-off points were compared to detect the optimal cut-off value for SII. Based on the ROC curve analysis, SII cut-off point of 574.20 showed 56.3% sensitivity and 45.5% specificity and with the Area Under Curve (AUC) 95% was the optimal cut-off point for active RA.This is the first study to review the Systemic Immune-Inflammation Index in rheumatoid arthritis. The obtained conclusion verified that the Systemic Immune-Inflammation Index could be used as a new tool, showing disease activity.