Association between Blood Biomarkers and Systemic Lupus Erythematosus Disease Activity: A Retrospective Study from Indonesia

Abstract

Background: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease, and laboratory parameters are essential for monitoring disease activity. Objectives: To determine the association between blood biomarkers and SLE disease activity in an Indonesian tertiary hospital. Methods: This retrospective study included adult patients with SLE treated at a tertiary hospital in Indonesia between January 2022 and August 2024. Patients were categorized into mild (inactive) or moderate–severe (active) disease activity groups, based on the MEX-SLEDAI score. Demographic and laboratory variables were collected. Receiver operating characteristic (ROC) analysis was done to assess discriminatory performance. Multivariate logistic regression was conducted to identify independent indicators of moderate–severe disease activity. Results: A total of 110 patients were included: 52 with active and 58 with inactive SLE. Between the groups, patients with active SLE had significantly lower hemoglobin (P < 0.001), hematocrit (P < 0.001), and platelet count (P = 0.019). In addition, significant differences were found for differential leukocyte counts and inflammatory hematological parameters, except the systemic immune-inflammation response index. ROC analysis showed that neutrophil percentage and neutrophil-to-lymphocyte ratio had the highest discriminatory performance (for both, AUC = 0.819), with optimal cut-offs of >68% (sensitivity: 67.3%; specificity: 87.9%) and >2.83 (sensitivity: 75.0%; specificity: 84.5%), respectively. In multivariate logistic regression, platelet count (P = 0.048) and eosinophil percentage (P = 0.026) were found to be independently associated with moderate–severe SLE activity. Conclusions: This study found that low platelet count and eosinopenia were independently associated with moderate–severe SLE disease activity, while neutrophil percentage and neutrophil-to-lymphocyte ratio demonstrated good discriminatory performance for distinguishing between active and inactive SLE.