Minimal proteinuria one year after transplant is a risk factor for graft survival in kidney transplantation

It is generally accepted that one-year post-transplant proteinuria over 0.5 gm per day has a negative impact on renal graft survival. In this study, the effects of minimal proteinuria less than 0.5 g/day were analyzed in 272 renal recipients who had survived for one year with a functioning graft. Recipients were classified by one-year post-transplant proteinuria: no proteinuria group (<0.2 g/day), minimal proteinuria group (0.2-0.5 g/day), and overt proteinuria group (>or=0.5 g/day). Recipients were followed up for 87.1+/-21 months after transplantation and 38 (13.9%) lost their graft during follow-up. Fifteen percent of patients had minimal proteinuria and 7.8% had overt proteinuria. Five-year graft survival in the minimal proteinuria group was 83.0%, and that in the overt proteinuria group was 70%, in contrast to 97.1% in the no proteinuria group (p=0.01 for trend). In a multivariate analysis, the minimal proteinuria group (relative risk [RR], 4.90; 95% confidence interval [CI], 2.09-11.46) and the overt proteinuria group (RR, 8.75; 95% CI, 3.29-23.29) had higher risks of graft failure than the no proteinuria group. Even minimal proteinuria at one year after transplantation was strongly associated with poor graft outcome. Therefore, it appears logical to consider a low level of proteinuria as a risk factor for graft survival in renal recipients.