Albuminuria after Induction Treatment and Kidney Prognosis in ANCA-associated Glomerulonephritis
Aglaia Chalkia, Rachel Jones, Rona Smith, Lisa Willcocks, David JayneAbstract
Introduction
It remains unclear whether persisting proteinuria in ANCA-associated glomerulonephritis (AAGN) reflects damage from the initial injury or ongoing inflammation.
Methods
A retrospective, single-centre study of biopsy-proven AAGN. The study defines the “albuminuria” group as urine albumin-to-creatinine ratio (ACR) greater than 300 mg/g and the “no albuminuria” group as ACR less than or equal to 300 mg/g at 6 months. We sought the clinical and histopathological characteristics of both the initial and subsequent biopsies and long-term kidney outcomes stratified by albuminuria levels.
Results
218 patients were included. Within the first six months, 28 (13%) 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 more often male (odds ratio [OR] 2.75; 95% CI 1.15-6.54), 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 (eGFR) was lower in the albuminuria group (adjusted mean difference in delta eGFR -12.5 ml/min per 1.73m2; 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 Berden classification and eGFR at diagnosis (Hazard ratio 6.53; 95% CI, 1.49 to 28.50).
Conclusions
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 eGFR at diagnosis.