#1337 Evolution of ANCA-associated vasculitis in a population with confirmed renal involvement. Myeloperoxidase and proteinase 3 antibodies, which is worse?

Abstract

Abstract Background and Aims Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of rare but potentially serious diseases with high mortality. Renal involvement is frequent in AAV with patients developing end-stage renal disease (ESRD) or becoming dependent on dialysis in up to 23% of patients. Several studies suggest the presence of clinical factors as predictors of survival in these diseases. The objective of this study was to analyze clinical evolution of AAV and to identify potential risk factors for developing renal events (ESRD or dialysis) and death in patients with AAV, with special attention to the implications that the presence of myeloperoxidase (MPO) or proteinase 3 (PR3) antibodies at diagnosis may have on the disease progression. Method We conducted a retrospective observational study of patients under follow-up for AAV. We considered only those with a confirmed diagnosis of AAV through renal biopsy for the present study. We collected clinical and laboratory variables at the time of disease presentation. We divided the patients based on the presence of MPO or PR3. Subsequently, we analyzed the patients' progression towards the occurrence of renal events (ESRD or dialysis) and mortality. Results Out of the 42 studied patients, 29 were MPO-positive and 13 were PR3-positive. We observed statistically significant differences in age and the frequency of hypertension, with the MPO group being older and more hypertensive than the PR3 group. On the contrary, PR3-positive patients exhibited a higher percentage of diabetes and increased severity of vasculitis at diagnosis as measured by the Birmingham Vasculitis Activity Score (BVAS). While most MPO-positive patients met criteria for microscopic polyangiitis (MPA), all PR3-positive patients met criteria for granulomatosis with polyangiitis (GPA) according to the ACR/EULAR 2022 guidelines. There were no statistically significant differences regarding clinical or laboratory variables analyzed, neither with induction nor maintenance treatment. We did not observe differences in the progression towards renal events or mortality between groups. However, we did observe a higher percentage of disease recurrence among PR3-positive patients (Table 1). Conclusion There were no statistically significant differences observed in the progression towards renal events (ESRD and dialysis) or mortality regardless of MPO or PR3 antibodies.