#1355 Albuminuria after Induction Treatment and Kidney Prognosis in ANCA-associated Glomerulonephritis

Abstract

Abstract Background and Aims Persisting proteinuria has been associated with worse kidney outcomes in ANCA-associated glomerulonephritis (AAGN). However, it remains unclear whether this reflects damage from the initial injury or ongoing inflammation. Method A retrospective, single centre study of biopsy-proven AAGN. The group “albuminuria” was defined as urine albumin-to-creatinine ratio (ACR) more than 300 mg/g and the group “no albuminuria”, defined as ACR less than or equal to 300 mg/g at 6 months. We sought the clinical and histopathological characteristics from both the initial and any subsequent biopsies, and long-term kidney outcomes stratified by albuminuria levels. Results 218 patients were included. Within the first six months, 28 (13%) had either died or progressed to end-stage kidney disease (ESKD). Among the remaining 190 patients, 37% had an ACR>300 mg/g at 6 months. The albuminuria group more frequently presented with a Berden mixed or crescentic class and had higher glomerular activity on the initial biopsy. They were also more often male [odds ratio (OR) 2.69; 95% CI 1.13-6.41], of younger age (OR 0.96; 95% CI, 0.93 to 0.99) and had fewer normal glomeruli in the biopsy (OR 0.96; 95% CI, 0.93 to 0.99) compared to the group without albuminuria. Over the initial 5-year period, the recovery in glomerular filtration rate (GFR) was lower in the albuminuria group (adjusted mean difference in delta GFR −12.5 ml/min per 1.73 m2; 95% CI, −15.8 to −9.1). In multivariable analysis, ACR greater than 300 mg/g was associated with a higher risk of ESKD, even after adjusting for age, Berden classification and GFR at diagnosis (Hazard ratio 7.25; 95% CI, 1.62 to 32.47). Conclusion In a well-defined cohort of AAGN, one third of the patients, primarily younger males with a lower percentage of normal glomeruli, had persisting albuminuria after induction treatment which was associated with worse kidney outcomes independent of Berden class and GFR at diagnosis.