Rarefaction of peritubular capillaries following ischemic acute renal failure: a potential factor predisposing to progressive nephropathy :

Delayed graft function (DGF) may be associated with diminished kidney allograft survival. We studied the risk factors that lead to nonimmediate function of a renal allograft and the consequences of DGF on short- and long-term renal transplant survival. Data from the U.S. Renal Data System were used to measure the relationships among cold ischemia time, delayed graft function, acute rejection, and graft survival in 37,216 primary cadaveric renal transplants (1985-1992). These relationships were investigated using the unconditional logistic and Cox multivariate regression methods. Cold ischemia time was strongly associated with DGF, with a 23% increase in the risk of DGF for every 6 hr of cold ischemia (P<0.001). Acute transplant rejection occurred more frequently in grafts with delayed function (37% vs. 20%; odds ratio=2.25, P=0.001). DGF was independently predictive of 5-year graft loss (relative risk=1.53, P<0.001). The presence of both early acute rejection and DGF portended a dismal 5-year graft survival rate of 35%. Zero-HLA mismatch conferred a 10-15% improvement in 1- and 5-year graft survival regardless of early functional status of the allograft. However, the 5-year graft survival rate in HLA-mismatched kidneys without DGF was significantly higher than that of zero-mismatched kidneys with DGF (63% vs. 51%; P<0.001). DGF independently portends a significant reduction in short- and long-term graft survival. Delayed function and early rejection episodes exerted an additive adverse effect on allograft survival. The deleterious impact of delayed function is comparatively more severe than that of poor HLA matching.

Improvements in long-term kidney graft survival have been recently noted. However, the reasons for this were unclear. This study examined post-transplant renal function within the first year as an independent variable influencing long-term survival. The influence of demographic characteristics (age, sex, race); transplant variables (cadaver versus living donor, cold ischemia time, HLA mismatching, delayed graft function and transplant year), and post-transplant variables (immunosuppressive agents for the prevention of acute rejection, clinical acute rejection and post-transplant renal function in the first year) on graft survival were analyzed for 105,742 adult renal transplants between 1988 and 1998. Renal function in the first year was expressed as serum creatinine at six months and one year and delta creatinine (change in serum creatinine between 6 months and 1 year). Graft half-life was used to measure long-term survival. During this 11-year period, the one-year serum creatinine values for cadaver recipients steadily improved, from 1.82 +/- 0.82 mg/dL in 1988 to 1.67 +/- 0.82 mg/dL in 1998 (P and < or =50 years. The Relative Hazard (RH) for graft failure was 1.63 (1.61, 1.65; P < 0.0001) with each increment of 1.0 mg/dL of serum creatinine at one year post-transplant and it increased to 2.26 (2.2, 2.31; P < 0.0001) when the Delta creatinine was 0.5 mg/dL. The RH reduction for graft failure was substantially lower for the years 1993, 1996, 1997 and 1998 when post-transplant renal function was not included in the model (P < 0.05). However, the RH reduction per year was not different when post-transplant creatinine was included in the model, 1.01 (0.94 to 1.05; P = 0.89). In conclusion, one-year creatinine and Delta creatinine values predict long-term renal graft survival. Recent improvements in graft half-life are related to conservation of renal function within the first year post-transplantation.