High anti-neutrophil cytoplasmic antibody titers are associated with the requirement of permanent dialysis in patients with myeloperoxidase-ANCA-associated vasculitis

Background/Purpose: A reliable noninvasive prognostic factor of ANCA-associated vasculitis (AAV) is still lacking, but little research has focused on the value of MPO-ANCA titers in patients with active vasculitis. This study explored the prognostic significance of MPO-ANCA titer in active AAV patients. Methods: Ninety-seven inpatients diagnosed with MPO-ANCA associated vasculitis at Linkou Chang Gung Memorial hospital and Keelung Chang Gung Memorial hospital from January 2005 to December 2016 were enrolled. Serum ANCA titers and basic characteristics of these patients at diagnosis were collected completely Medical records since AAV diagnosis were reviewed to evaluate two years renal and patient outcome. Results: The patients were divided into the two groups according to the median ANCA titers, the more than four times of the normal cut-off value group (high titer group) and the less ANCA titer group (low titer group). The high titer group had significant poor initial renal function (eGFR 16.7 vs 40.7 mL/min/1.73 m², P = 0.006), and significantly lower two-year renal survival (Log rank P < 0.001). Whereas patient survival (Log rank P = 0.894) was not different The Cox regression models revealed that baseline Birmingham Vasculitis Activity Score, eGFR and a 4-fold increase in ANCA titer were associated with the requirement of permanent dialysis. In the subgroup analysis, the ANCA titer was still an important risk factor for renal outcomes (P = 0.036) in patients with better initial renal function (eGFR≧15 mL/min). Conclusion: This study demonstrated that higher MPO-ANCA titers at diagnosis was associated with poor initial renal function and 2-year renal outcomes.