Residual proteinuria and eGFR predict progression of renal impairment within 2 years in type 2 diabetic patients with nephropathy who are receiving optimal treatment with angiotensin receptor blockers

Aim Proteinuria and estimated glomerular filtration rate (eGFR) predict progression of renal impairment in type 2 diabetic nephropathy (DN) but are they still predictive when these patients are treated with angiotensin receptor blockers (ARB)? We investigated whether residual (after 3 months of ARB treatment) urinary protein/creatinine ratio (rPCR) or urinary albumin/creatinine ratio (rACR) and residual eGFR (reGFR), predict subsequent progression. Methods One thousand, two hundred and forty-five patients with type 2 DN from two international multi-center studies were analysed. Cross classification of rPCR, rACR with reGFR (rPCR: <1000, 1000-<2000 and 2000mg/g; rACR: <666.7, 666.7-<1333.3 and 1333.3 mg/g; reGFR: 15-29, 30-44 and 45-59 mL/min per 1.73 m2). Progression of renal disease exhibited as: end stage renal failure, doubling of serum creatinine, or serum creatinine 6 mg/dL. Results Increasing rPCR or rACR, and decreasing reGFR were strongly associated with increasing risk of renal disease progression, with no evidence of interaction between rPCR and reGFR, or rACR and reGFR. The estimated 24-month risk was low (<8%) for patients with rPCR <1000 mg/g regardless of reGFR, for patients with reGFR 45 mL/min per 1.73 m2 regardless of rPCR, or with rPCR between 1000-<2000 mg/g and reGFR 30 mL/min per 1.73 m2. However, the risk rose steeply (to 39.4%) for reGFR <30 mL/min per 1.73 m2 and rPCR 2000 mg/g. Conclusion Despite DN patients being treated with ARB, renal disease progression risk over 2 years increases with increasing proteinuria, albuminuria and decreasing eGFR. Recognition of these risk factors' impact is important in patient management and future clinical trial design.