The clinical significance of early proteinuria after renal transplantation.

BACKGROUND

Late-onset proteinuria after renal transplantation has been universally associated with poor allograft outcomes. However, the significance of early low-grade posttransplant proteinuria remains uncertain.

METHODS

We analyzed the effect of proteinuria 3 months posttransplantation on death-censored graft loss, death with a functioning graft, vascular events within the graft's life, and estimated glomerular filtration rate at 5 years. Four hundred seventy-seven renal transplants from a single center (1988-2003) with a mean follow-up of 122 months were divided into four groups based on the median protein creatinine ratio (PCR) during the 3rd posttransplant month (PCR<0.15 [group 1, n=85]; PCR 0.15-0.5 [group 2, n=245]; PCR 0.5-1.00 [group 3, n=96]; PCR>1.00 [group 4, n=51]). Cox proportional hazards analysis was performed to study the impact of proteinuria on the various outcomes.

RESULTS

Multivariate analysis revealed that even low-level proteinuria at 3 months predicted death-censored graft failure (group 1 [reference]--hazard ratio [HR]=1, group 2--HR=7.1, group 3--HR = 10.5, group 4--HR 16.0; P=0.001). The impact on death and the occurrence of vascular events was only significant for group 4 (HR: 2.6; P=0.01 for death and HR: 2.2; P=0.04 for vascular events). Estimated glomerular filtration rate at 5 years was group 1, 48.5 mL/min; group 2, 41.2 mL/min; group 3, 31.1 mL/min; and group 4, 24.5 mL/min (P<0.001). Continued observation of group 2 to 1 year revealed adverse outcomes with increasing proteinuria.

CONCLUSIONS

Low-grade proteinuria at 3 months is associated with adverse clinical outcomes and identifies high-risk group of patients who may benefit from further intervention.