Screening for renal involvement in ANCA-associated vasculitis: Room for improvement?

Background: Renal involvement in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) requires prompt and aggressive immunosuppressive therapy. The aim of this study was to evaluate screening practice for renal involvement in AAV and its potential effect on renal outcomes. Methods: Between 2005 and 2015, ANCA-positive AAV patients in a teaching hospital in the Netherlands were retrospectively included. Complete screening for renal involvement was defined as: assessment of erythrocyturia, proteinuria and serum creatinine within two weeks of the diagnosis of AAV. Characteristics at presentation and at 12 months were compared between patients with and without complete screening. Results: A total of 109 AAV patients (63% male) were identified with a mean age of 62 ± 14 years. Complete screening for renal involvement was performed in 90 of the 109 patients (83%). Patients with incomplete screening had a lower serum creatinine (86 ± 53 vs. 190 ± 185 µmol/l, p < 0.001) and were more often diagnosed outside the renal department (100% vs. 78%, p = 0.02). Three patients with incomplete screening had a rise in serum creatinine of ≥ 30% at 12 months. Incomplete screening was not associated with the development of end-stage renal disease. Urine analysis of patients with renal biopsy-proven AAV (n = 31) showed erythrocyturia in 58% after one sample and in 94% after three samples. Conclusion: Screening for renal involvement in AAV was suboptimal, primarily in patients who presented outside the renal department. A higher sensitivity for erythrocyturia is achieved if urine analysis is repeated. Incomplete screening may lead to renal impairment if renal involvement is not treated appropriately.