Association Between Baseline Modified Novel Fibrosis Index and Subsequent Stroke in Patients with Microscopic Polyangiitis or Granulomatosis with Polyangiitis

Background and Objectives: This study investigated whether the baseline modified novel fibrosis index (mNFI) could predict subsequent stroke in patients with microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA). Materials and Methods: This study included 268 patients with MPA or GPA who met the inclusion and exclusion criteria. Clinical data at diagnosis were collected. Baseline Birmingham Vasculitis Activity Score (BVAS), Five-Factor Score (FFS), and earliest Vasculitis Damage Index (eVDI) were recorded as MPA/GPA-specific indices, and erythrocyte sedimentation rate and C-reactive protein (CRP) levels were recorded as acute-phase reactants. mNFI was derived by deleting the constant ‘N’ from the NFI formula and was calculated as follows: serum bilirubin (mg/dL) × (alkaline phosphatase [IU/L])2 / platelet count (× 1000/mm3) / (serum albumin [g/dL])2. Results: Among the 268 patients with MPA (70.9%) or GPA (29.1%), the median age was 62.0 years, and 64.6% were women. During a median follow-up of 55.1 months, stroke occurred in 7.1% of patients. Baseline mNFI correlated significantly with age, FFS and CRP, but not with BVAS or eVDI. Multivariable Cox proportional hazards analysis showed that baseline mNFI (hazard ratio 1.079) was independently associated with subsequent stroke alongside CRP levels. Patients with baseline mNFI ≥1.08 had a higher risk of subsequent stroke and a lower cumulative stroke-free survival rate than those with baseline mNFI < 1.08. Conclusions: Baseline mNFI was associated with subsequent stroke in patients with MPA or GPA and may represent a readily available candidate marker for cerebrovascular risk assessment. Further validation is required before its routine clinical application.