Persistent hematuria in patients with antineutrophil cytoplasmic antibody-associated vasculitis during clinical remission: chronic glomerular lesion or low-grade active renal vasculitis?

Background: Whether persistent hematuria in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) during clinical remission reflects active disease or chronic glomerular injury is uncertain. This study aimed to investigate the significance of persistent hematuria during clinical remission in a large cohort of AAV patients. Methods: A cohort of 219 AAV patients in complete clinical remission after induction therapy at our center was retrospectively studied, and their clinical and laboratory data as well as long-term outcomes were analyzed. Results: A total of 80 out of 219 patients had persistent hematuria during clinical remission of AAV. Compared with patients without hematuria during remission, the slope of eGFR decline in patients with persistent hematuria was significantly higher during the long-term follow-up [ 3.6 (IQR 1.2, 7.2) vs. 1.5 (IQR 0.2, 4.0) mL/min/1.73 m(2)/year, P < 0.001]. Among the 80 patients with persistent hematuria during remission, there was little difference between those with fast and slow decline of eGFR, as divided by either median or interquartile range of the slope of eGFR decline. We also compared patients without hematuria who had a slope of eGFR decline that was lower than the median level of the slope of eGFR decline with those with persistent hematuria, and found that patients with hematuria had significantly lower levels of CRP and ESR at baseline and higher levels of ANCA at remission. Conclusions: Among the AAV patients who achieved clinical remission after immunosuppressive therapy, those with persistent hematuria are not rare and may reflect either chronic renal damage or low-grade active renal disease.