Kidney Donor Profile Index of Marginal Donors
Kidney Donor Profile Index of Marginal Donors
Pretransplant donor biopsy (PTDB)-based marginal donor allocation systems to single or dual renal transplantation could increase the use of organs with Kidney Donor Profile Index (KDPI) in the highest range (e.g. >80 or >90), whose discard rate approximates 50% in the United States. To test this hypothesis, we retrospectively calculated the KDPI and analyzed the outcomes of 442 marginal kidney transplants (340 single transplants: 278 with a PTDB Remuzzi score <4 [median KDPI: 87; interquartile range (IQR): 78–94] and 62 with a score = 4 [median KDPI: 87; IQR: 76–93]; 102 dual transplants [median KDPI: 93; IQR: 86–96]) and 248 single standard transplant controls (median KDPI: 36; IQR: 18–51). PTDB-based allocation of marginal grafts led to a limited discard rate of 15% for kidneys with KDPI of 80–90 and of 37% for kidneys with a KDPI of 91–100. Although 1-year estimated GFRs were significantly lower in recipients of marginal kidneys (−9.3, −17.9 and −18.8 mL/min, for dual transplants, single kidneys with PTDB score <4 and =4, respectively; p < 0.001), graft survival (median follow-up 3.3 years) was similar between marginal and standard kidney transplants (hazard ratio: 1.20 [95% confidence interval: 0.80–1.79; p = 0.38]). In conclusion, PTDB-based allocation allows the safe transplantation of kidneys with KDPI in the highest range that may otherwise be discarded.
The increasing number of patients on the waiting lists for kidney transplantation has not been paralleled by a similar growth in the number of available donors. More worrisome is the fact that over 20% of available kidneys are from donors who are older than 65 years, or have diabetes or renal impairment, and are therefore frequently not considered suitable for donation, due to the increased risk of early failure of their organs.
In the United States, despite the implementation of the expanded criteria donor (ECD) program over 10 years ago, the percentage of kidneys recovered but not transplanted remains over 40%. Major determinants of discard rates are biopsy findings on wedge biopsy (percent glomerulosclerosis) and parameters of machine pump perfusion. The United Network of Organ Sharing (UNOS) Kidney Transplantation Committee has recently approved a new allocation policy, that will be implemented by the end of 2014 which is based on the Kidney Donor Risk Index (KDRI), that represents the relative risk of posttransplant graft failure from a particular deceased donor compared to the average donor. The Kidney Donor Profile Index (KDPI) is an additional numerical score, which results from ranking KDRI from the 1st to the 100th percentile, with reference to a given Organ Procurement and Transplantation Network (OPTN) donor cohort. Among organs retrieved between 2002 and 2012, 36% and 63% of kidneys with KDPI 80–90 and >90 were discarded, respectively.
Starting with the rationale that poor long-term outcome of marginal grafts is the consequence of an imbalance between the number of viable nephrons supplied, and the metabolic demand of the recipient, a standardized assessment of pretransplant donor biopsies (PTDBs) has been proposed to estimate nephron mass. This estimate allows discrimination between kidneys that would provide outcomes similar to standard organs and those that should be discarded. Histological evaluation can also identify kidneys with suboptimal nephron mass that should not be transplanted alone, but may be suitable if used in dual transplantation.
Although the histological criteria to allocate grafts to single or dual transplantation or to discard them are still not uniform, there is evidence suggesting that this strategy might help in recovering marginal kidneys which would be otherwise discarded, without affecting patient outcomes.
The aim of the present study was to test the hypothesis that a standardized PTDB assessment-based allocation approach allows identification of kidneys with KDPI in the highest range that are suitable for single or dual transplantation. To this end, we examined the KDPI distribution and outcomes of 442 marginal kidneys allocated to single or dual transplantation exclusively on the basis of a standardized assessment of PTDB. We also included in our analyses 248 control recipients of single standard kidney transplants.
Abstract and Introduction
Abstract
Pretransplant donor biopsy (PTDB)-based marginal donor allocation systems to single or dual renal transplantation could increase the use of organs with Kidney Donor Profile Index (KDPI) in the highest range (e.g. >80 or >90), whose discard rate approximates 50% in the United States. To test this hypothesis, we retrospectively calculated the KDPI and analyzed the outcomes of 442 marginal kidney transplants (340 single transplants: 278 with a PTDB Remuzzi score <4 [median KDPI: 87; interquartile range (IQR): 78–94] and 62 with a score = 4 [median KDPI: 87; IQR: 76–93]; 102 dual transplants [median KDPI: 93; IQR: 86–96]) and 248 single standard transplant controls (median KDPI: 36; IQR: 18–51). PTDB-based allocation of marginal grafts led to a limited discard rate of 15% for kidneys with KDPI of 80–90 and of 37% for kidneys with a KDPI of 91–100. Although 1-year estimated GFRs were significantly lower in recipients of marginal kidneys (−9.3, −17.9 and −18.8 mL/min, for dual transplants, single kidneys with PTDB score <4 and =4, respectively; p < 0.001), graft survival (median follow-up 3.3 years) was similar between marginal and standard kidney transplants (hazard ratio: 1.20 [95% confidence interval: 0.80–1.79; p = 0.38]). In conclusion, PTDB-based allocation allows the safe transplantation of kidneys with KDPI in the highest range that may otherwise be discarded.
Introduction
The increasing number of patients on the waiting lists for kidney transplantation has not been paralleled by a similar growth in the number of available donors. More worrisome is the fact that over 20% of available kidneys are from donors who are older than 65 years, or have diabetes or renal impairment, and are therefore frequently not considered suitable for donation, due to the increased risk of early failure of their organs.
In the United States, despite the implementation of the expanded criteria donor (ECD) program over 10 years ago, the percentage of kidneys recovered but not transplanted remains over 40%. Major determinants of discard rates are biopsy findings on wedge biopsy (percent glomerulosclerosis) and parameters of machine pump perfusion. The United Network of Organ Sharing (UNOS) Kidney Transplantation Committee has recently approved a new allocation policy, that will be implemented by the end of 2014 which is based on the Kidney Donor Risk Index (KDRI), that represents the relative risk of posttransplant graft failure from a particular deceased donor compared to the average donor. The Kidney Donor Profile Index (KDPI) is an additional numerical score, which results from ranking KDRI from the 1st to the 100th percentile, with reference to a given Organ Procurement and Transplantation Network (OPTN) donor cohort. Among organs retrieved between 2002 and 2012, 36% and 63% of kidneys with KDPI 80–90 and >90 were discarded, respectively.
Starting with the rationale that poor long-term outcome of marginal grafts is the consequence of an imbalance between the number of viable nephrons supplied, and the metabolic demand of the recipient, a standardized assessment of pretransplant donor biopsies (PTDBs) has been proposed to estimate nephron mass. This estimate allows discrimination between kidneys that would provide outcomes similar to standard organs and those that should be discarded. Histological evaluation can also identify kidneys with suboptimal nephron mass that should not be transplanted alone, but may be suitable if used in dual transplantation.
Although the histological criteria to allocate grafts to single or dual transplantation or to discard them are still not uniform, there is evidence suggesting that this strategy might help in recovering marginal kidneys which would be otherwise discarded, without affecting patient outcomes.
The aim of the present study was to test the hypothesis that a standardized PTDB assessment-based allocation approach allows identification of kidneys with KDPI in the highest range that are suitable for single or dual transplantation. To this end, we examined the KDPI distribution and outcomes of 442 marginal kidneys allocated to single or dual transplantation exclusively on the basis of a standardized assessment of PTDB. We also included in our analyses 248 control recipients of single standard kidney transplants.
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