Kidney biopsy in patients with glomerulonephritis: is the earlier the better?

BACKGROUND Interventional diagnostic procedures are established for several diseases in medicine. Despite the KDOQI guideline recommendation for histological diagnosis of kidney disease to enable risk stratification, its optimal time point has not been evaluated. We have therefore analyzed whether histological diagnosis of glomerulonephritis (GN) at an early stage of chronic kidney disease (CKD) is associated with different outcome compared to diagnosis at a more advanced stage. METHODS A cohort of 424 consecutive patients with histological diagnosis of GN were included in a retrospective data analysis. Kidney function was assessed by glomerular filtration rate (GFR) estimation at the time point of kidney biopsy and after consecutive immunosuppressive therapy. Censored events were death, initiation of dialysis or kidney transplantation, or progression of disease, defined as deterioration of CKD stage ≥ 1 from kidney biopsy to last available kidney function measurement. RESULTS Occurrence of death, dialysis/transplantation or progression of disease were associated with GFR and CKD stage at the time of kidney biopsy (p < 0.001 for all). Patients with CKD stage 1 and 2 at kidney biopsy had fewer endpoints compared to patients with a GFR of <60 ml/min (p < 0.001). CONCLUSION Kidney function at the time point of histological GN diagnosis is associated with clinical outcome, likely due to early initiation of specific drug treatment. This suggests that selection of therapy yields greatest benefit before renal function is impaired in GN.