THU0106 SYSTEMIC IMMUNE-INFLAMMATION INDEX IN RHEUMATOID ARTHRITIS PATIENTS: RELATION TO DISEASE ACTIVITY

Background: Among the immune system elements, neutrophils, lymphocytes and platelets play a role in the regulation of inflammation while also undergoing changes secondary to inflammation. Recently, the neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) have been used as markers of systemic inflammation including rheumatoid arthritis (RA). It was reported that systemic immune-inflammation index (SII) is positively correlated with neutrophil and platelet counts and inversely correlated with lymphocyte count. Objectives: We investigated whether SII in RA patients and compare between active cases and those in remission. Methods: This research is a cross-sectional study. In 734 RA patients registered in the database of our department from January to April in 2016, a total of 574 eligible RA patients were included in this study, excluding 160 patients whose neither RA disease activity or laboratory data were available. Correlations of SII with the disease activity of RA were evaluated. SII was calculated by the following calculation formula; SII = Netrophils (%)/Lymphocyte (%) * Platelets (G/L). Results: The median age of patients was 65.0 (IQR: 53.0-73.0) years and the median of disease duration was 9.0 (6.0-14.0) years. The DAS28-ESR was median 2.65 (1.90 - 3.37). SII was 612.0 (400.6 – 951.8). There was a significant correlation between SII and DAS28-ESR (r=0.322, P<0.0001), and SII was significantly elevated as disease activity increased (median 513.6 in remission group, 605.7 in low disease activity group, 793.8 in moderate disease activity group and 1367.1 in high disease activity group, respectively; P<0.00001). In contrast to SII, in NLR no significant difference was observed in all groups. The cut-off of SII was 635.9, 688.6 and 912.5 for DAS28-ESR remission, low disease activity and high disease activity. In multiple regression analysis of LogSII, compared to conventional DMARDs treatment, anti-cytokine therapy such as anti-IL-6 receptor inhibitor or anti-TNF inhibitor showed a significant negative correlation, but no significant differences were observed with abatacept or JAK inhibitor. Conclusion: In this study, for the first we demonstrated that SII was more strongly related to disease activity than NLR. SII is an emerging inflammatory biomarker which could be used to evaluate disease activity in RA patients. A larger scale longitudinal study is recommended to confirm the present results and further demonstrate the relation to medications received and disease outcome. Disclosure of Interests: Takahiro Yoshikawa: None declared, Tetsuya Furukawa: None declared, Masao Tamura: None declared, Teppei Hashimoto: None declared, Mai Morimoto: None declared, Naoto Azuma: None declared, Masayasu Kitano: None declared, Kiyoshi Matsui Grant/research support from: Asahi Kasei, Astellas