FAR in systemic lupus erythematosus: a potential biomarker of disease activity and lupus nephritis.

The fibrinogen-to-albumin ratio (FAR), a novel inflammatory marker, has been studied in various diseases. However, the significance of FAR in systemic lupus erythematosus (SLE) has not been fully elucidated. This study was to investigate the connection between FAR and SLE. A retrospective analysis of 154 SLE patients and 77 healthy individuals was performed. The clinical and laboratory data were reviewed. Receiver operating characteristic (ROC) curves were conducted for FAR at baseline to predict disease activity and lupus nephritis (LN) in SLE patients. Pearson correlation was also applied. FAR in the SLE group was found to be significantly higher than that of the healthy control group (83.71 mg/g vs. 53.14 mg/g, P < 0.001). It was also significantly higher in patients with LN than that in patients without (107.64 mg/g vs. 67.75 mg/g, P < 0.001). The ROC curve for predicting LN showed that the area under the curve (AUC) of FAR (0.859, 95% CI 0.803-0.914) was the largest when compared to albumin (0.852, 95% CI 0.789-0.916) or fibrinogen (0.736, 95% CI 0.659-0.814) alone. In addition, FAR was a good predictor of severe disease activity in SLE (AUC = 0.721, 95% CI 0.612-0.830) and LN patients (AUC = 0.789, 95% CI 0.680-0.898). Pearson correlation analysis indicated that FAR demonstrated a strong correlation with SLE disease activity index 2000 (r = 0.4288, P < 0.001). FAR was significantly increased in SLE patients. It is a possible biomarker for disease activity and renal involvement in SLE.