Kidney involvement is common in ANCA associated vasculitis (AAV) and prognosis determined by the severity of kidney damage. This study focused on long-term kidney outcomes, defining possible risk factors and comparing the performance of three different histological classifications to predict outcomes for patients with AAV.
The dataset included 848 patients with newly diagnosed AAV who participated in 7 RCTs (1995-2012). Follow up information obtained from questionnaires sent to the principal investigators of the original RCTs.
The cumulative incidence of end-stage kidney disease (ESKD) at 5 and 10 years was 17% and 22%, respectively. Patients who developed ESKD had reduced patient survival compared to those with preserved kidney function (HR: 2.8, P-value < 0.001). Comparing patients with AAV and kidney involvement to a matched general population, patients with AAV had poor survival outcomes, even in early stages of CKD. The main cause of death was infection followed by cardiovascular disease in patients developing ESKD and malignancy in those who did not. 34% of patients with initial need for dialysis recovered kidney function after treatment. 35 out of 175 in need of kidney replacement therapy (KRT) during follow up received a kidney transplant with good outcome; 86% patient survival at 10 years.In the subcohort of 214 patients with available kidney biopsies, three scoring systems were tested: the Berden classification, the Renal Risk Score (RRS), and the Mayo Clinic Score (MCCS). The scores highlighted the importance of normal glomeruli and severe glomerulosclerosis on kidney survival (P < 0.001 and P = 0.001, respectively). The RRS demonstrated a moderate prediction of kidney survival (AUC: 0.79; SE: 0.03, 95% CI: 0.71-0.83).
Early diagnosis is extremely important. Even milder forms of kidney involvement have an impact on the prognosis. Patients in need of KRT had the lowest survival rates, but kidney transplantation has shown favorable outcomes for eligible AAV patients. The three histologic scoring systems were all identified as independent prognostic factors for kidney outcome.