Serum syndecan1 has the potential to reflect activity at diagnosis and predict death during follow-up in patients with ANCA-associated vasculitis

This study investigated whether serum syndecan1 at diagnosis reflects activity at diagnosis and predicts poor outcomes during follow-up in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The study included 79 patients with AAV from the cohort of Korean patients diagnosed with AAV. AAV-specific indices, including the Birmingham vasculitis activity score (BVAS), five-factor score (FFS), 36-item short-form survey (SF-36) physical and mental component summary (PCS and MCS), and vasculitis damage index (VDI), were assessed. Laboratory data including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were also collected. The highest tertile and upper half of the BVAS were tentatively defined as having high AAV activity. Serum syndecan1 levels were measured in sera stored at diagnosis. Serum syndecan1 at diagnosis was significantly correlated with AAV activity and functional status, as assessed by BVAS, FFS, SF-36 PCS, MCS, and acute-phase reactants, including ESR and CRP. Patients with serum syndecan1 ≥ 76.1 ng/mL at diagnosis, and those with serum syndecan1 ≥ 60.0 ng/mL at diagnosis showed significantly higher risks for the highest tertile and the upper half of BVAS at diagnosis than those without, respectively. Patients with serum syndecan1 ≥ 120.1 ng/mL at diagnosis had a significantly higher risk for all-cause mortality during follow-up than those without, and further, exhibited a significantly lower cumulative patients’ survival rate than those without. Serum syndecan1 at diagnosis may not only reflect AAV activity at diagnosis but may also be associated with all-cause mortality during follow-up.