Systemic inflammation response index (SIRI) as a novel biomarker in patients with rheumatoid arthritis: a multi-center retrospective study

Objectives To evaluate the potential ability of systemic inflammation response index (SIRI) as a novel biomarker in patients with rheumatoid arthritis (RA) and explore the mechanisms. Method Patients fulfilling the 2010 ACR/EULAR classification criteria for RA were enrolled in this study. Demographic, clinical, and laboratory characteristics of all subjects were collected. Neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR), platelet/lymphocyte ratio (PLR), and SIRI were calculated. Statistical analysis was performed, and P -values < 0.05 were considered statistically significant. Results One thousand four hundred ninety-nine RA patients from five hospitals were included, with 366 healthy volunteers served as controls. The NLR, MLR, PLR, and SIRI significantly increased in RA patients. Receiver operating characteristics (ROC) curve analysis showed SIRI, and NLR could distinguish RA from healthy controls. Correlation analysis and multiple linear regression analysis indicated that SIRI and PLR positively correlated with disease activity in RA. The NLR, MLR, and SIRI increased significantly in patients with RA-associated interstitial lung disease (ILD). There was a good accuracy of SIRI in differentiating RA-ILD from RA patients without ILD. SIRI was also found to be higher in RA patients with tumor and could differentiate them from RA patients without tumor. Conclusions SIRI could be evaluated as a novel, non-invasive, and suitable biomarker for assisting in the diagnosis process and demonstrating the disease activity of RA, as well as predicting RA-ILD and tumor development of RA patients. Key Points • As a novel biomarker, systemic inflammation response index (SIRI) may assist in the diagnosis process and indicate the disease activity of RA patients • SIRI may predict the development of RA-associated interstitial lung disease (RA-ILD) and tumor in RA patients • SIRI is more satisfactory than other blood cells-based indexes in the assessment of RA patients