Urinary T Lymphocytes Predict Renal Flares in Patients With Inactive ANCA-associated Glomerulonephritis

Inclusion Criteria: * diagnosed ANCA-associated vasculitis (clinical diagnosis of granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis or microscopic polyangiitis consistent with the Chapel-Hill consensus definitions AND positive test for proteinase 3-ANCA or myeloperoxidase-ANCA) * no currently active renal involvement (defined as BVAS = 0 with exception of hematuria or proteinuria as signs of renal scars) * written and informed consent Exclusion Criteria: * urinary tract infection * active menstrual bleeding * active renal involvement * other active renal disease (e.g. diabetic nephropathy) Initially, we defined treatment with rituximab as exclusion criteria. However, upon closer examination, we recognized that this exclusion criterion was overly restrictive and may have inadvertently excluded eligible participants who met our other inclusion criteria. As a result of this reassessment, we have revised our exclusion criteria to no longer exclude individuals solely on the basis of receiving rituximab treatment.