Peripheral Blood Neutrophil-to-Lymphocyte Ratio Combined With Fibrinogen-to-Albumin Ratio Assists in Identifying Systemic Lupus Erythematosus Activity and Lupus Nephritis.

This retrospective study explored the relationship of serum neutrophil-to-lymphocyte ratio (NLR) and fibrinogen-to-albumin ratio (FAR) with disease activity and lupus nephritis (LN) in systemic lupus erythematosus (SLE) and assessed the clinical value of the derived combination model. Patients (N = 147) with SLE were enrolled in the final analysis. Peripheral blood NLR and FAR also differed between subgroups based on LN absence/presence: LN (79 cases) and non-LN groups (68 cases) were independently associated with SLE disease activity and LN onset according to univariate and multivariate logistic regression results. Crucially, the NLR and FAR composite model demonstrated potentially auxiliary performance superior to the conventional indicator composite model (anti-dsDNA, complement C3/C4, 24-h UPr), yielding an area under the ROC curve (AUC) of 0.865 for severe disease activity (95% CI: 0.799-0.915, sensitivity: 0.833, specificity: 0.769) and 0.922 for LN development (95% CI: 0.867-0.962, sensitivity: 0.785, specificity: 0.941). In conclusion, peripheral blood NLR and FAR may serve as potentially useful auxiliary biomarkers for identifying severe disease activity and LN in patients with SLE. These exploratory findings were obtained from a single-center, small-scale population. Therefore, multi-center prospective cohort studies with large-scale populations are needed to confirm their clinical applicability and generalizability.