GRN and anti-neutrophil cytoplasmic antibody-associated vasculitis: Multivariable analysis of data from patients with serum progranulin higher than 55.16 ng/ml identified FFS (OR 27.127, 95% CI 1.254, 586.817) and ESR (OR 1.091, 95% CI 1.013, 1.175) but not serum progranulin ≥55.16 ng/ml as independent predictors of the cross‐sectional severe AAV.