Systemic Immune-Inflammation Index as a Potential Biomarker for Assessing Disease Activity and Predicting Proteinuria Development in Systemic Lupus Erythematosus.

Background Systemic lupus erythematosus (SLE) is a complex autoimmune disease with varied clinical manifestations affecting multiple organ systems. This study aimed to investigate the association between the systemic immune-inflammation index (SII) and disease activity, as well as proteinuria levels in patients with SLE. Methodology A total of 141 patients diagnosed with SLE and 99 control subjects were included in this retrospective study. SLE patients were divided into two groups based on the presence (52) or absence (89) of proteinuria. Demographic data, laboratory parameters, and disease activity scores were recorded. SII was calculated based on peripheral blood counts. Statistical analysis was performed to assess the relationship between SII levels and disease activity, as well as proteinuria. Results The statistical analysis among the three groups revealed that SII was significantly different in all three groups (p < 0.001). Moreover, within the SLE cohort, patients with proteinuria had significantly higher SII levels compared to those without proteinuria (p = 0.012). Correlation analysis revealed a positive association between SII and both proteinuria and Systemic Lupus Erythematosus Disease Activity Index 2000 (r = 0.215; p = 0.011 and r = 0.186; p = 0.028, respectively). Receiver operating characteristic analysis demonstrated that SII had potential clinical value in diagnosing SLE and predicting proteinuria development. Conclusions The findings of this study suggest that SII may serve as a useful biomarker for assessing disease activity and predicting proteinuria development in patients with SLE. Further research is warranted to validate these findings and explore the utility of SII in clinical practice for monitoring disease progression and treatment response in SLE.