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.