Permanent detrimental effect of nonimmunological factors on long-term renal graft survival: a parsimonious model of time-dependency.

Purpose. We attempted to model and test the pattern of effects of prognostic factors on renal graft survival during the posttransplantation time course. Patients and methods. Patients who received a cadaveric kidney-only transplant between January 1990 and December 1995 in Eurotransplant,(7) who received cyclosporine as induction therapy, and who had a complete follow-up at the time of analysis were included in the study (n=10614). An index summarizing all covariate information was calculated and used for modeling the time-dependent effects with relation to graft failure. Results. The immunological factors (HLA mismatch and % panel-reactive antibody) were seen to have a slowly decreasing negative effect on renal graft survival. The cold ischemic trauma (>24 hr) exerted a permanent detrimental effect on the grafts. The use of organs obtained from old donors was associated with a constant higher risk of graft loss. Conclusions. An analysis of determinants of human allograft dysfunction should also study the interaction between the effects and time. Nonimmunological factors had a constant detrimental effect on graft failure, whereas the impact of the immunological factors-although remaining important for late graft loss-very slowly decreased. In the context of marginal transplants, clustering of unfavorable factors should be avoided to prevent late graft losses.