Renal involvement in ANCA-associated vasculitis

Aim

We assessed the frequency, clinical features and outcomes of renal involvement in patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA).

Material and methods

We studied 374 patients with ANCA-associated vasculitides (AAV), diagnosed according to the ACR criteria and Chapel Hill Consensus Conference 2012 classification. Serum creatinine (sCr) levels, estimated glomerular filtration rates, levels of hematuria and daily proteinuria were measured. Doubling of sCr levels within ≤3 months was considered as the clinical equivalent of rapidly progressive glomerulonephritis (RPGN).

Results

Renal involvement was diagnosed in 183 (48.9%) patients with AAV. Kidney involvement was significantly more common in MPA (96.9%) compared with GPA (44.0%) and EGPA (22.7%) (P≤0.001). Patients with MPA had significantly higher median levels of proteinuria and hematuria and developed hypertension and RPGN more often than patients with GPA and EGPA (P<0.017). End-stage renal disease (ESRD) developed in 10.9% of patients. Baseline sCr and its rapid increase before induction remission therapy predicted ESRD (P<0.05). By the end of the follow up, 49.7% of patients were at high or very high risk of chronic kidney disease (CKD) progression according to KDIGO (2012) guidelines despite effective immunosuppressive therapy. Myeloperoxidase-ANCApositive patients had higher median levels of hematuria and proteinuria and developed RPGN and hypertension significantly more often than proteinase-3-ANCA-positive patients (P<0.05).

Conclusion

The frequency and clinical features of renal involvement depend both on the nosologic form of AAV and type of ANCA. Half of the patients in remission are still at high risk of CKD progression.

Key words

ANCA-associated vasculitis, rapidly progressive glomerulonephritis, chronic kidney disease.