Fibrinogen to albumin ratio reflects the activity of antineutrophil cytoplasmic antibody-associated vasculitis

Background: We investigated whether fibrinogen to albumin ratio (FAR) at diagnosis could reflect the cross-sectional activity and predict poor outcomes in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Methods: This cross-sectional study included 54 immunosuppressant drug-naïve patients with AAV who had the results of plasma fibrinogen and serum albumin at diagnosis. Clinical and laboratory data at diagnosis were collected, and all-cause mortality, cerebrovascular accident, cardiovascular disease, end-stage renal disease occurrences were assessed as poor outcomes. FAR was calculated by the following equation: FAR = plasma fibrinogen (g/dl)/serum albumin (g/dl). Results: The median age was 65.5 years, and 59.3% of patients were men (33 MPA, 13 GPA and 8 EGPA). FAR was significantly correlated with Birmingham vasculitis activity score (BVAS; r = 0.271), erythrocyte sedimentation rate (ESR; r = 0.668) and C-reactive protein (CRP; r = 0.638). High BVAS was defined as BVAS ≥16, and the cut-off of FAR at diagnosis was set as 0.118. AAV patients with FAR at diagnosis ≥0.118 had a significantly higher risk for the cross-sectional high BVAS than those without (RR 3.361). In the univariable linear regression analysis, CRP (β = 0.383) and FAR (β = 0.297) were significantly correlated with BVAS at diagnosis. However, in the multivariable analysis, none of them was correlated with the cross-sectional BVAS. FAR at diagnosis could not predict poor outcomes during follow-up in AAV patients. Conclusions: Fibrinogen to albumin ratio at diagnosis could reflect the cross-sectional BVAS but could not predict poor outcomes in patients with AAV.