Clinical characteristics and outcomes of MPO-ANCA-associated glomerulonephritis with bronchiectasis: A retrospective case-control study

The association of bronchiectasis with myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (MPO-AAV) has been widely described in recent studies. However, the clinical features and outcomes of MPO-ANCA-associated glomerulonephritis (MPO-ANCA GN) patients with bronchiectasis remain enigmatic. MPO-ANCA GN patients with bronchiectasis were compared to MPO-ANCA GN patients alone. Clinical imaging, pathological tests, and follow-up examination data of patients were collected retrospectively. Progression to end-stage renal disease (ESRD) and death was treated as endpoint events. 153 cases (52 patients with bronchiectasis) were included in this study. Compared to MPO-ANCA GN patients alone, MPO-ANCA GN patients with bronchiectasis exhibited a lower level of proteinuria (p = 0.019) and relatively higher eGFR level. MPO-ANCA GN patients with bronchiectasis had less frequent incidences of interstitial lung disease (ILD) and emphysema (p<0.001, p = 0.016, respectively) but with higher rates of pulmonary infection (p<0.001). Bronchiectasis severity (the modified Reiff score) was positively correlated with MPO antibody titers (ρ=0.480, p<0.001), but not with shorter renal survival. A relatively higher remission rate was been seen in MPO-ANCA GN patients with bronchiectasis, who showed reduced susceptibility in progressing to ESRD in multivariate analysis (p = 0.043, HR=0.542, 95% CI 0.299–0.982). One-and three-year overall survival rates were 88.2% and 77.3% for MPO-ANCA GN with bronchiectasis cases versus 83.7% and 67.2% for MPO-ANCA GN patients alone (p = 0.431, p = 0.241, respectively). The severity of bronchiectasis was correlated with anti-MPO antibody titers in MPO-ANCA GN patients. For MPO-ANCA GN patients, bronchiectasis associated with good renal prognosis, but it did not improve overall survival.