Similar outcomes with different rates of delayed graft function may reflect center practice, not center performance

Abstract

To better understand the implications for considering delayed graft function (DGF) as a performance measure, we compared outcomes associated with a 2- to 3-fold difference in the incidence of DGF at two transplant centers. We analyzed 5072 kidney transplantations between 1984 and 2006 at the University of Minnesota Medical Center (UMMC) and Hennepin County Medical Center (HCMC). In logistic regression the adjusted odds ratio for DGF at HCMC versus UMMC was 3.11 (95% Confidence Interval [CI]= 2.49-3.89) for deceased donors and 2.24 (CI = 1.45-3.47) for living donors. In Cox analysis of 4957 transplantations, slow graft function (SGF; creatinine >or=3.0 mg/dL [230 micromol/L] on day 5 without dialysis) was associated with graft failure at UMMC (Relative Risk [RR]= 1.43, CI = 1.25-1.64), but not HCMC (RR = 0.99, CI = 0.77-1.28). RR's of DGF were similar at both centers. Thus, the lower incidence of DGF at UMMC likely resulted in a higher incidence and higher risk of SGF compared to HCMC. Indeed, graft survival for recipients with DGF at HCMC was similar (p = 0.3741) to that of recipients with SGF at UMMC. We conclude that dialysis per se is likely not a cause of worse graft outcomes. A better definition is needed to measure early graft dysfunction and its effects across transplant programs.

Figure 1

Graft survival in patients without delayed graft function or slow graft function. Patients thought to have graft failure in the first week (primary nonfunction) were excluded. Shown are comparisons between living and deceased donor transplants, at the UMMC and HCMC. P-values are by the log-rank test. Abbreviations: UMMC, University of Minnesota Medical Center; HCMC, Hennepin County Medical Center; N, the number remaining with functioning grafts at each year of follow up for living and deceased donor transplantations at UMMC and HCMC, respectively.

Figure 2

Graft survival in patients with delayed graft function. Patients thought to have graft failure in the first week (primary nonfunction) were excluded. Shown are comparisons between living and deceased donor transplants, at the UMMC and HCMC. P-values are by the log-rank test. Abbreviations: UMMC, University of Minnesota Medical Center; HCMC, Hennepin County Medical Center; N, the number remaining with functioning grafts at each year of follow up for living and deceased donor transplantations at UMMC and HCMC, respectively.

Figure 3

Graft survival in patients with slow graft function. Patients thought to have graft failure in the first week (primary nonfunction) were excluded. Shown are comparisons between living and deceased donor transplants, at the UMMC and HCMC. P-values are by the log-rank test. Abbreviations: UMMC, University of Minnesota Medical Center; HCMC, Hennepin County Medical Center; N, the number remaining with functioning grafts at each year of follow up for living and deceased donor transplantations at UMMC and HCMC, respectively.

Figure 4

Graft survival comparing patients with SGF at UMMC to patients with DGF at HCMC. Patients thought to have graft failure in the first week (primary nonfunction) were excluded. Shown are comparisons between living and deceased donor transplants, at the UMMC and HCMC. P-values are by the log-rank test. Abbreviations: UMMC, University of Minnesota Medical Center; HCMC, Hennepin County Medical Center; N, the number remaining with functioning grafts at each year of follow up for living and deceased donor transplantations at UMMC and HCMC, respectively.