Systemic Immune-inflammation Index: A Potential Indicator of Disease Activity in Sjögren's Syndrome?

Abstract

Given the autoimmune and inflammatory nature of Sjögren's Syndrome(SS), it is essential to identify reliable indicators to monitor disease progression and inform treatment strategies. This study aims to evaluate the potential of the Systemic Immune-Inflammation Index (SII) as a biomarker for assessing disease activity in SS.  A prospective analysis was conducted on two groups: the first comprising 52 patients diagnosed with SS and the second a healthy control group. SII values were calculated using the following formula: platelet count multiplied by the neutrophil-to-lymphocyte ratio. The degree of disease activity was gauged according to the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI) criteria. This study examines the correlations between SII and several clinical and patient-reported outcome measures, including various inflammatory markers. Compared to the control group, the SS patient cohort displayed slightly elevated SII levels (p = 0.04). The SII exhibited a correlation with elevated levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), suggesting its potential as a marker of systemic inflammation. Nevertheless, the observed correlation between SII and ESSDAI scores (r = 0.0903) was weak and not statistically significant (p = 0.524). Although SII values were higher in SS patients and correlated with systemic inflammation markers, no statistically significant relationship was observed between these values and disease activity, as measured by ESSDAI.Thus, while SII may reflect systemic inflammation, its utility as a marker for disease activity in SS remains limited. Further studies are needed to elucidate its role in clinical settings.