Prognostic Significance of Creeping Proteinuria in the First Year After Transplantation.

Background: Proteinuria changes have a prognostic significance in proteinuric nephropathies. Proteinuria has been related to kidney transplant outcomes, but there are no information about the impact of increasing proteinuria during the first year on long-term graft and patient survival.

Methods: Retrospective cohort study of 591 kidney transplants to analyze the effect on long-term prognosis of: proteinuria at 3 (n = 591) and 12 (n = 583) months (no proteinuria: 150-299 mg/24 hours, 300-999 mg/24 hours, and ≥1 g/24 hours), and changes in proteinuria during the first year in such patients with proteinuria at 3 months (reduction ≥50% of proteinuria from 3 to 12 months, variation <50%, and increase ≥50% or "creeping proteinuria") (n = 283).

Results: Higher levels of proteinuria, at both 3 and 12 months, were progressively related to lower graft survival (P < 0.0001). Proteinuria at 12 months was related to mortality (P = 0.026). Creeping proteinuria, which was present in 35 patients (12.4%), was related to graft failure (P < 0.0001) and mortality (P = 0.030), even at lower levels of proteinuria at 3 months. De novo HLA antibody development was the only factor related to creeping proteinuria (hazard ratio, 2.946; 95% confidence interval, 1.158-7.491; P = 0.023).

Conclusions: Creeping proteinuria during the first year was associated with long-term graft failure and mortality and could be considered as a surrogate of kidney disease progression in the renal transplant population, as it is in proteinuric nephropathies. It could also be viewed as an expression of immunological damage.