Relationship between serologic profile (ANCA type) and clinical features of renal involvement in ANCA-associated vasculitides

Objective. To compare the frequency, clinical features and outcomes of renal involvement in ANCA-associated vasculitides (AAV) in patients with antibodies against proteinase-3 (pr3-ANCA) and myeloperoxidase (MPO-ANCA). Materials and methods. In our retrospective study we enrolled 264 patients, 94 males and 170 females, median age 53 [36; 62] years. Among them 157 were pr3-ANCA positive and 107 were MPO-ANCA positive. AAV was diagnosed according to ACR criteria and Chapel Hill consensus conference definition (2012). Median follow up was 44 [18; 93] months. We assessed baseline BVAS and VDI by the end of the follow up. Serum creatinine (sCr), estimated glomerular filtration rate (eGFR), hematuria and daily proteinuria were estimated. Diagnosis and stage of chronic kidney disease (CKD) and acute kidney injury (AKI) were established according to KDIGO guidelines (2012) and Scientific Society of Russian Nephrologists (2016). Results. Renal involvement was present in 181 (68.6%) patients, and its frequency was similar in pr3-ANCA and MPO-ANCA subgroups. Patients with MPO-ANCA developed rapidly progressive glomerulonephritis and hypertension significantly more often than patients with pr3-ANCA: 50.7% vs 35.6% (p=0.049) and 46.1% vs 29.8% (p=0.029) respectively. At disease onset, median sCr was significantly higher and eGFR was significantly lower in patients with MPO-ANCA (p<0.05). 1-year and 5-year renal survival rates were similar in pr3-ANCA-positive (93.9% and 87.4% respectively) and MPO-ANCA positive patients (87.4% and 83.1% respectively). Median BVAS and VDI scores were significantly higher in pr3-ANCA subgroup. The number of patients who developed AAV relapse during 1-year follow up was also significantly higher in pr3-ANCA subgroup. The frequency of eye and ENT involvement was significantly higher in pr3-ANCA positive patients than in MPO-ANCA-positive patients. Conclusions: The frequency of extrarenal manifestations, clinical features of renal involvement and relapse rate are associated with AAV serotype.