ATP5MK and anti-neutrophil cytoplasmic antibody-associated vasculitis: Background and Objectives: This study investigated whether serum alpha-1-acid glycoprotein (AGP) at diagnosis could reflect the cross-sectional activity represented by the Birmingham vasculitis activity score (BVAS) and further predict poor outcomes during follow-up in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).