Determinants of discard of expanded criteria donor kidneys: impact of biopsy and machine perfusion

Associations of Perfusate Biomarkers and Pump Parameters With Delayed Graft Function and Deceased Donor Kidney Allograft Function

Hypothermic machine perfusion (HMP) is increasingly used in deceased donor kidney transplantation, but controversy exists regarding the value of perfusion biomarkers and pump parameters for assessing organ quality. We prospectively determined associations between perfusate biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], kidney injury molecule 1, IL-18 and liver-type fatty acid-binding protein [L-FABP]) and pump parameters (resistance and flow) with outcomes of delayed graft function (DGF) and 6-mo estimated GFR (eGFR). DGF occurred in 230 of 671 (34%) recipients. Only 1-h flow was inversely associated with DGF. Higher NGAL or L-FABP concentrations and increased resistance were inversely associated with 6-mo eGFR, whereas higher flow was associated with higher adjusted 6-mo eGFR. Discarded kidneys had consistently higher median resistance and lower median flow than transplanted kidneys, but median perfusate biomarker concentrations were either lower or not significantly different in discarded compared with transplanted kidneys. Notably, most recipients of transplanted kidneys with isolated "undesirable" biomarker levels or HMP parameters experienced acceptable 6-mo allograft function, suggesting these characteristics should not be used in isolation for discard decisions. Additional studies must confirm the utility of combining HMP measurements with other characteristics to assess kidney quality.

Association Between Organ Procurement Organization Social Network Centrality and Kidney Discard and Transplant Outcomes

BACKGROUND

Given growth in kidney transplant waitlists and discard rates, donor kidney acceptance is an important problem. We used network analysis to examine whether organ procurement organization (OPO) network centrality affects discard and outcomes.

METHODS

We identified 106,160 deceased donor kidneys recovered for transplant from 2000 to 2010 in Scientific Registry of Transplant Recipients. We constructed the transplant network by year with each OPO representing a node and each kidney-sharing relationship between OPOs representing a directed tie between nodes. Primary exposures were the number of different OPOs to which an OPO has given a kidney or from which an OPO has received a kidney in year preceding procurement year. Primary outcomes were discard, cold-ischemia time, delayed graft function, and 1-year graft loss. We used multivariable regression, restricting analysis to the 50% of OPOs with highest discard and stratifying remaining OPOs by kidney volume. Models controlled for kidney donor risk index, waitlist time, and kidney pumping.

RESULTS

An increase in one additional OPO to which a kidney was given by a procuring OPO in a year was associated with 1.4% lower likelihood of discard for a given kidney (odds ratio, 0.986; 95% confidence interval, 0.974-0.998) among OPOs procuring high kidney volume, but 2% higher likelihood of discard (odds ratio, 1.021; 95% confidence interval, 1.006-1.037) among OPOs procuring low kidney volume, with mixed associations with recipient outcomes.

CONCLUSIONS

Our study highlights the value of network analysis in revealing how broader kidney sharing is associated with levels of organ acceptance. We conclude interventions to promote broader inter-OPO sharing could be developed to reduce discard for a subset of OPOs.

Epidemiology of Kidney Discard from Expanded Criteria Donors Undergoing Donation after Circulatory Death

BACKGROUND AND OBJECTIVES

The broader use of combined expanded criteria donor and donation after circulatory death (ECD/DCD) kidneys may help expand the deceased donor pool. The purpose of our study was to evaluate discard rates of kidneys from ECD/DCD donors and factors associated with discard.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

ECD/DCD donors and kidneys were evaluated from January 1, 2000 to March 31, 2011 using data from the Scientific Registry of Transplant Recipients. The kidney donor risk index was calculated for all ECD/DCD kidneys. Multivariable logistic regression models were used to determine risk factors for discarding both donor kidneys. The Kaplan-Meier product limit method and the log-rank statistic were used to assess the cumulative probability of graft failure for transplants from ECD/DCD donors where the mate kidney was discarded versus both kidneys were used.

RESULTS

There were 896 ECD/DCD donors comprising 1792 kidneys. Both kidneys were discarded in 44.5% of donors, whereas 51.0% of all available kidneys were discarded. The kidney donor risk index scores were higher among donors of discarded versus transplanted kidneys (median, 1.82; interquartile range, 1.60, 2.07 versus median, 1.67; interquartile range, 1.49, 1.87, respectively; P<0.001); however, the distributions showed considerable overlap. The adjusted odds ratios for discard were higher among donors who were older, diabetic, AB blood type, and hepatitis C positive. The cumulative probabilities of total graft failure at 1, 3, and 5 years were 17.3%, 36.5%, and 55.4% versus 13.8%, 24.7%, and 40.5% among kidneys from donors where only one versus both kidneys were transplanted, respectively (log rank P=0.04).

CONCLUSIONS

Our study shows a significantly higher discard rate for ECD/DCD kidneys versus prior reports. Some discarded ECD/DCD kidneys may be acceptable for transplantation. Additional studies are needed to evaluate the factors that influence decision making around the use of ECD/DCD kidneys.

High-Resolution Imaging Using the VisualSonics Vevo 2100 on Isolated, Perfused Porcine Kidneys on Mechanical Circulatory Support

Despite many improvements in the field of renal transplantation, the key problem that persists is the lack of organs for all the patients who need kidneys. This problem continues despite the addition of extended criteria donors and donation after cardiac death. Compounding this issue is the high discard rate and there are no good means to truly predict renal function using current pretransplantation testing parameters. In an isolated renal perfusion model using porcine kidneys, we tested the proof of principle that a Vevo 2100 high-frequency high-resolution ultrasound system (Fujifilm VisualSonics, Inc., Toronto, Canada) could assess renal parenchymal perfusion and flow in the central renal vessels which could not assess by conventional ultrasound. Images and velocities were easily obtained during these studies. High-frequency ultrasound imaging may be a feasible and reproducible method for assessing renal parenchymal integrity and function pretransplantation. Further studies are required to determine the sensitivity and specificity of this approach in comparison with traditional renal biopsy pretransplantation with the goal of increasing the identification and use of donated kidneys for transplantation.

Successful transplantation of kidneys from elderly circulatory death donors by using microscopic and macroscopic characteristics to guide single or dual implantation

Most kidneys from potential elderly circulatory death (DCD) donors are declined. We report single center outcomes for kidneys transplanted from DCD donors over 70 years old, using preimplantation biopsy Remuzzi grading to inform implantation as single or dual transplants. Between 2009 and 2012, 43 single transplants and 12 dual transplants were performed from elderly DCD donors. Remuzzi scores were higher for dual than single implants (4.4 vs. 3.4, p < 0.001), indicating more severe baseline injury. Donor and recipient characteristics for both groups were otherwise similar. Early graft loss from renal vein thrombosis occurred in two singly implanted kidneys, and in one dual-implanted kidney; its pair continued to function satisfactorily. Death-censored graft survival at 3 years was comparable for the two groups (single 94%; dual 100%), as was 1 year eGFR. Delayed graft function occurred less frequently in the dual-implant group (25% vs. 65%, p = 0.010). Using this approach, we performed proportionally more kidney transplants from elderly DCD donors (23.4%) than the rest of the United Kingdom (7.3%, p < 0.001), with graft outcomes comparable to those achieved nationally for all deceased-donor kidney transplants. Preimplantation biopsy analysis is associated with acceptable transplant outcomes for elderly DCD kidneys and may increase transplant numbers from an underutilized donor pool.

Pretransplant biopsy in expanded criteria donors: do we really need it?

INTRODUCTION

Renal transplantation is the best treatment for end-stage renal disease, including when using expanded criteria donors (ECD) kidneys. However, these suboptimal kidneys should be evaluated rigorously to meet their usefulness. Opinions differ about the best way to evaluate them.

MATERIALS AND METHODS

We retrospectively reviewed kidneys from ECD harvested by a single academic institution between January 2008 and September 2013. Needle biopsies were performed at the time of the harvest when considered relevant by the transplant team. Two pathologists where responsible for their analysis; the Remuzzi classification has been used in all cases.

RESULTS

We evaluated 560 ECD kidneys. Biopsies were made in 197 (35.2%) organs, 20 of which were considered not usable and 36 good only for double transplantation. Sixty-three kidneys (11.3%) were discarded by the transplant team based on the biopsy result and clinical criteria. Donors who underwent a biopsy were older (P < .001) and had a worse glomerular filtration rate (GFR; P = .001). Comparing donors approved and rejected by the biopsy, the rejected donors were heavier (P = .003) and had a lower GFR (P = .002). Cold ischemia time was longer for the biopsy group (P < .001). Regarding graft function, the biopsy overall score correlated with the transplant outcome in the short and long term. Separately, glomeruli and interstitium scores were correlated with recipient's GFR in the earlier periods (3 months; P = .025 and .037), and the arteries and tubules correlated with GFR in the longer term (at 3 years P = .004 and .010).

CONCLUSION

The decision on the usability of ECD grafts is complex. At our center, we chose a mixed approach based on donor risk. Low-risk ECD do not require biopsy. In more complex situations, especially older donors or those with a lower GFR, prompted a pretransplant biopsy. The biopsy results proved to be useful as they relate to subsequent transplant outcomes, thereby allowing us to exclude grafts whose function would most probably be less than optimal.

New Solutions to Reduce Discard of Kidneys Donated for Transplantation

Kidney transplantation is a cost-saving treatment that extends the lives of patients with ESRD. Unfortunately, the kidney transplant waiting list has ballooned to over 100,000 Americans. Across large areas of the United States, many kidney transplant candidates spend over 5 years waiting and often die before undergoing transplantation. However, more than 2500 kidneys (>17% of the total recovered from deceased donors) were discarded in 2013, despite evidence that many of these kidneys would provide a survival benefit to wait-listed patients. Transplant leaders have focused attention on transplant center report cards as a likely cause for this discard problem, although that focus is too narrow. In this review, we examine the risks associated with accepting various categories of donated kidneys, including discarded kidneys, compared with the risk of remaining on dialysis. With the goal of improving access to kidney transplant, we describe feasible proposals to increase acceptance of currently discarded organs.

Geographic Variation in Cold Ischemia Time: Kidney vs. Liver Transplantation in the United States, 2003-2011

Background

Regional variations in kidney and liver transplant outcomes have been reported, but their causes remain largely unknown. This study investigated variations in kidney and liver cold ischemia times (CITs) across organ procurement organizations (OPO) as potential causes of variations in transplant outcomes.

Methods

This retrospective study analyzed the Standard Transplant Analysis and Research data of deceased donor kidney (n = 61,335) and liver (n = 39,285) transplants performed between 2003 and 2011. The CIT variations between the 2 types of organs were examined and compared. Factors associated with CIT were explored using multivariable regressions. Spearman rank tests were used to associate CIT with graft failure at the OPO level.

Results

Significant CIT variations were found across OPOs for both organs (P < 0.05). The variation was particularly large for kidney CIT. Those OPOs with longer average kidney CIT were likely to have a lower graft survival rate (P = 0.01). For liver, this association was insignificant (P = 0.23). The regression analysis revealed sharp contrasts between the factors associated with kidney and liver CITs. High-risk kidney transplant recipients and marginal kidneys were associated with longer average CIT. The reverse was true for liver transplants.

Conclusions

Large variations in kidney CIT compared to liver CIT may indicate that there is a room to reduce kidney CIT. Reducing kidney CIT through managerial improvements could be a cost-effective way to improve the current transplant system.

Long term outcomes of transplantation using kidneys from expanded criteria donors: prospective, population based cohort study

OBJECTIVES

To assess the long term outcomes of transplantation using expanded criteria donors (ECD; donors aged ≥ 60 years or aged 50-59 years with vascular comorbidities) and assess the main determinants of its prognosis.

DESIGN

Prospective, population based cohort study.

SETTING

Four French referral centres.

PARTICIPANTS

Consecutive patients who underwent kidney transplantation between January 2004 and January 2011, and were followed up to May 2014. A validation cohort included patients from another four referral centres in France who underwent kidney transplantation between January 2002 and December 2011.

MAIN OUTCOME MEASURES

Long term kidney allograft survival, based on systematic assessment of donor, recipient, and transplant clinical characteristics; preimplantation biopsy; and circulating levels of donor specific anti-HLA (human leucocyte antigen) antibody (DSA) at baseline.

RESULTS

The study included 6891 patients (2763 in the principal cohort, 4128 in the validation cohort). Of 2763 transplantations performed, 916 (33.2%) used ECD kidneys. Overall, patients receiving ECD transplants had lower allograft survival after seven years than patients receiving transplants from standard criteria donors (SCD; 80% v 88%, P<0.001). Patients receiving ECD transplants who presented with circulating DSA at the time of transplantation had worse allograft survival after seven years than patients receiving ECD kidneys without circulating DSA at transplantation (44% v 85%, P < 0.001). After adjusting for donor, recipient, and transplant characteristics, as well as preimplantation biopsy findings and baseline immunological parameters, the main independent determinants of long term allograft loss were identified as allocation of ECDs (hazard ratio 1.84 (95% confidence interval 1.5 to 2.3); P < 0.001), presence of circulating DSA on the day of transplantation (3.00 (2.3 to 3.9); P < 0.001), and longer cold ischaemia time (> 12 h; 1.53 (1.1 to 2.1); P = 0.011). Recipients of ECD kidneys with circulating DSA showed a 5.6-fold increased risk of graft loss compared with all other transplant therapies (P < 0.001). ECD allograft survival at seven years significantly improved with screening and transplantation in the absence of circulating DSA (P < 0.001) and with shorter (<12 h) cold ischaemia time (P=0.030), respectively. This strategy achieved ECD graft survival comparable to that of patients receiving an SCD transplant overall, translating to a 544.6 allograft life years saved during the nine years of study inclusion time.

CONCLUSIONS

Circulating DSA and cold ischaemia time are the main independent determinants of outcome from ECD transplantation. Allocation policies to avoid DSA and reduction of cold ischaemia time to increase efficacy could promote wider implement of ECD transplantation in the context of organ shortage and improve its prognosis.

The Donor Kidney Biopsy and Its Implications in Predicting Graft Outcomes: A Systematic Review

Despite a growing organ shortage in the United States, many deceased donor kidneys removed for transplantation are discarded. Kidney biopsy findings often play a role in these discards, although it is not clear whether biopsies reliably inform acceptance decisions. Therefore, we carried out a systematic review of the medical literature on the utility of both procurement and implantation biopsies for predicting posttransplant outcomes. Between January 1, 1994 and July 1, 2014, 47 studies were published in the English language literature that examined the association between pretransplant donor biopsy findings from 50 or more donors (with more than half being from deceased donors) and either posttransplant graft failure, delayed graft function, or graft function. In general, study quality was poor. All were retrospective or did not indicate if they were prospective. Results were heterogeneous, with authors as often as not concluding that biopsy results did not predict posttransplant outcomes. The percent glomerular sclerosis was most often examined, and failed to predict graft failure in 7 of 14 studies. Of 15 semiquantitative scoring systems proposed, none consistently predicted posttransplant outcomes across studies. Routine use of biopsies to help determine whether or not to transplant a kidney should be reexamined.

Machine Perfusion: Not Just for Marginal Kidney Donors

Interest in machine perfusion (MP) for donated kidneys has markedly increased in the past decade as a means to improve graft function, although the donor populations in which it should be applied have not yet been resolved. All adults undergoing de-novo isolated kidney transplantation from standard-criteria donors in the UNOS database 2005 to 2011 were reviewed with the primary endpoint of delayed graft function (DGF), defined as dialysis within seven days of transplantation, in those who received kidneys that underwent MP versus cold storage (CS) alone. Three methods were used to control for differences between groups. Multivariable logistic regression was performed, adjusting for donor and recipient characteristics significantly associated with DGF. Rates were also compared in a cohort of propensity-matched MP vs CS recipients. Finally, a paired-kidney study was performed, where one kidney underwent MP and the contralateral underwent CS. There were 36,323 patients, with unadjusted DGF rates of 18.6 per cent (n = 1830/9882) and 22.4 per cent (n = 5931/26,441; P < 0.001) in the MP vs CS groups, respectively. After multivariable analysis, the odds ratio for DGF in the MP group was 0.59 ( P < 0.001) versus CS. In the propensity-matched cohort, there were 8929 patients each in the MP and CS groups. DGF occurred in 16.8 per cent of the MP group vs 25.3 per cent with CS ( P < 0.001, OR 0.59). In the paired-kidney study, rates of DGF were 16.7 per cent vs 24.3 per cent ( P < 0.001) in the 1665 recipients each in the MP versus CS groups (OR 0.6). In conclusion, machine perfusion is beneficial in reducing DGF even when standard donors are utilized, and thus should not be limited to marginal kidneys.

Associations of deceased donor kidney injury with kidney discard and function after transplantation

Deceased donor kidneys with acute kidney injury (AKI) are often discarded due to fear of poor outcomes. We performed a multicenter study to determine associations of AKI (increasing admission-to-terminal serum creatinine by AKI Network stages) with kidney discard, delayed graft function (DGF) and 6-month estimated glomerular filtration rate (eGFR). In 1632 donors, kidney discard risk increased for AKI stages 1, 2 and 3 (compared to no AKI) with adjusted relative risks of 1.28 (1.08-1.52), 1.82 (1.45-2.30) and 2.74 (2.0-3.75), respectively. Adjusted relative risk for DGF also increased by donor AKI stage: 1.27 (1.09-1.49), 1.70 (1.37-2.12) and 2.25 (1.74-2.91), respectively. Six-month eGFR, however, was similar across AKI categories but was lower for recipients with DGF (48 [interquartile range: 31-61] vs. 58 [45-75] ml/min/1.73m(2) for no DGF, p < 0.001). There was significant favorable interaction between donor AKI and DGF such that 6-month eGFR was progressively better for DGF kidneys with increasing donor AKI (46 [29-60], 49 [32-64], 52 [36-59] and 58 [39-71] ml/min/1.73m(2) for no AKI, stage 1, 2 and 3, respectively; interaction p = 0.05). Donor AKI is associated with kidney discard and DGF, but given acceptable 6-month allograft function, clinicians should consider cautious expansion into this donor pool.

Baseline donor chronic renal injury confers the same transplant survival disadvantage for DCD and DBD kidneys

Histological assessment of baseline chronic kidney injury may discriminate kidneys that are suitable for transplantation, but has not been validated for appraisal of donation after circulatory death (DCD) kidneys. 'Time-zero' biopsies for 371 consecutive, solitary, deceased-donor kidneys transplanted at our center between 2006 and 2010 (65.5% DCD, 34.5% donation after brain death [DBD]) were reviewed and baseline chronic degenerative injury scored using Remuzzi's classification. High scores correlated with donor age and extended criteria donors (42% of donors), but the spectrum of scores was similar for DCD and DBD kidneys. Transplant outcomes for kidneys scoring from 0 to 4 were comparable (1 and 3 year graft survival 95% and 92%), but were much poorer for kidneys scoring ≥5, with 1 year graft survival only 73%, and 12.5% suffering primary nonfunction. Critically, high Remuzzi scores conferred the same survival disadvantage for DCD and DBD kidneys. On multi-variable regression analysis, time-zero biopsy score was the only independent predictor for graft survival, whereas one-year graft estimated glomerular filtration rate (eGFR) correlated with donor age and biopsy score. In conclusion, the relationship between severity of chronic kidney injury and transplant outcome is similar for DCD and DBD kidneys. Kidneys with Remuzzi scores of ≤4 can be implanted singly with acceptable results.

Hypothermic machine perfusion of kidneys retrieved from standard and high-risk donors

Hypothermic machine perfusion (HMP) of kidneys is a long-established alternative to static cold storage and has been suggested to be a better preservation method. Today, as our deceased donor profile continues to change towards higher-risk kidneys of lower quality, we are confronted with the limits of cold storage. Interest in HMP as a preservation technique is on the rise. Furthermore, HMP also creates a window of opportunity during which to assess the viability and quality of the graft before transplantation. The technology might also provide a platform during which the graft could be actively repaired, making it particularly attractive for higher-risk kidneys. We review the current evidence on HMP in kidney transplantation and provide an outlook for the use of the technology in the years to come.

Can only histological evaluation determine the allocation of ECD kidneys?

INTRODUCTION

There is a recent debate on the "transplantability" of ECD (Expanded Criteria Donors) kidneys and the selection criteria used to allocate them to single or double transplantation. Remuzzi et al. have defined a protocol incorporating pre-transplant donor biopsy to guide the use of older donor organs. They allocated organs as single or double transplants on the basis of histological findings. We aim to show the pros and cons of the only histological evaluation in the allocation of ECD kidneys, to compare the different experiences in United States and Europe and thus to discuss whether this tool should be used alone or included in a comprehensive clinical and histopathological evaluation.

DISCUSSION

In the United States many Authors stated that the biopsy actually increases the percentage of kidney discarded and they raised questions about the importance of the biopsy in evaluating ECD kidneys for transplantation. On the other hand, the experiences of the majority of european transplant centers showed that allocating kidneys as single or dual transplant based on biopsy findings may achieve good graft and patient outcomes. Moreover, the experience of some centers as ours showed that kidneys allocated as DKT (Dual Kidney Transplant) on the basis of Remuzzi's score could have been suitable for single transplantation suggesting the need of an adjustment of the Remuzzi Score System. Many Authors, who are in favor of histological evaluation, actually believe that a comprehensive clinical and histopathological assessment before transplantation remains necessary. We lack precise national- or international-based selection criteria to guide clinicians. An adjustment of the Remuzzi Score System could be taken into consideration such as narrowing the indication for DKT from those ECD kidneys with higher scores and including the histological evaluation in a multifactor score.

Poor organ quality and donor-recipient age mismatch rather than poor donation rates account for the decrease in deceased kidney transplantation rates in a Germany Transplant Center

Kidney transplantation is limited not by technical or immunological challenges but by lack of donor organs. Whereas the number of patients on waiting list increased, the transplantation rate decreased. We analyzed the development of decline rates and reasons as well as the fate of declined organs. In total, 1403 organs offered to 1950 patients between 2001 and 2010 were included. Of 440 organs offered between 2009 and 2011 that were declined, we investigated whether these organs were transplanted elsewhere and requested delayed graft function, creatinine, graft and patient survival. Data were compared to results of transplantations at the same time at our center. Decline rate increased from 47% to 87%. Main reasons were poor organ quality and donor-recipient age or size mismatch. Of the rejected organs, 55% were transplanted at other centers with function, graft and patient survival equivalent to patients transplanted at our center during that period. The number of decline has increased over time mainly due to a growing number of marginal donors accounting for poor organ quality or a mismatch of donor and recipient. If proper donor-recipient selection is performed, many organs that would otherwise be discarded can be transplanted successfully.

A single-center experience with 200 dual kidney transplantations

This study reports on a large series of 200 dual kidney transplantations (DKTs) from expanded criteria donors (ECDs) and proposes specific ways to optimize outcomes. Data concerning 200 DKTs performed in the last 14 yr were retrospectively analyzed. Kidneys from high-risk ECD were allocated for use in DKTs on an old-for-old basis after histological assessment. Different surgical techniques and immunosuppressant regimens were used over time, and the outcomes are discussed. Donors and recipients were a median 73 (70-77) and a 62 (58-67) yr old, respectively. Delayed graft function occurred in 31.5% of cases, and acute rejection in 13.5%. Patient and graft survival at five yr were 90.4% and 85.8%, respectively. Unilateral kidney placement was preferred for 75% of patients, and was associated with a low rate of surgical complications. Our current standard therapy comprising low-dose calcineurin inhibitors (CNIs) associated with mammalian target of rapamycin inhibitors (mTOR) and steroids appears to offer the best risk/benefit profile for elderly patients undergoing DKT. In our experience, outcomes after DKT can be improved by: (i) kidney clinical-histological assessment; (ii) unilateral kidney placement; (iii) minimal use of CNI associated with mTOR.

The Kidney Donor Profile Index (KDPI) of marginal donors allocated by standardized pretransplant donor biopsy assessment: distribution and association with graft outcomes

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.

Donor Kidney Evaluation

In patients with end-stage renal disease, kidney transplantation is the best means to extend survival and offer a better quality of life. The current shortage of organs available for transplantation has led to an effort to expand the kidney donor pool, including the use of nonideal donor kidneys. Assessment of the quality of the donated kidney is essential, and would facilitate the decision to transplant a potential organ or discard it. Multiple clinical and histologic parameters have been examined to evaluate the donor kidney and relate the findings to the graft outcome, but clear-cut criteria are yet to be defined.

Investigation of apoptosis-related gene expression levels in preimplantation biopsies as predictors of delayed kidney graft function

BACKGROUND

The purpose of this study was to investigate the expression of the gene coding for the antiapoptotic molecule Bcl-2, the proapoptotic molecule Bax, and the apoptosis executor enzyme caspase-3 in preimplantation renal biopsies (PIB) as markers for delayed graft function.

METHODS

In this prospective single-center study, gene expression levels were evaluated using real-time TaqMan polymerase chain reaction in PIB of kidneys from 72 deceased donors (DDs) and 18 living donors (LDs).

RESULTS

CASP3 and BAX expression levels were higher, whereas those of BCL2 were lower, in DD than in LD PIB. In biopsies from DD, BCL2 levels were lower in cases with DGF, whereas no differences were observed concerning CASP3 and BAX. The BAX/BCL2 gene expression ratio greater than 2.29 associated with DGF with an odds ratio of 2.00. A multiple regression analysis including data of TLR4 expression in the first day posttransplant PB from a previous study of our group conducted in the same patients revealed a very strong association of the combination of BAX/BCL2 greater than 2.3 in PIB and TLR4 of 0.95 uRE or lesser in PB with the occurrence of DGF, with OR of 120 and positive and negative predictive values of 91% and 92%, respectively.

CONCLUSIONS

The power to predict DGF of the combination of high BAX/BCL2 expression in PIB and low TLR4 expression in the first day posttransplant peripheral blood observed in the present study is extremely high, in comparison to any other marker or combinations of markers so far published in the literature.

Preoperative assessment of the deceased-donor kidney: from macroscopic appearance to molecular biomarkers

Variation in deceased-donor kidney quality can significantly affect outcomes after kidney transplantation. Suboptimal organ selection for a given recipient can result in primary nonfunction, premature graft failure, or inappropriate discard of a suitable organ. Appraisal and appropriate selection of deceased-donor kidneys for use in transplantation is therefore critical. A number of predictive tools have been developed to assist the transplant team in evaluating the suitability of a deceased-donor kidney for transplantation to a given recipient. These include stratification of donors into "standard-" or "expanded-criteria" categories based on clinical parameters, pre-implantation biopsy scores, donor risk scores, machine perfusion characteristics, functional kidney weight, donor biomarkers and molecular diagnostic tools, ex vivo viability assessment using postmortem normothermic perfusion, and overall macroscopic appraisal by the surgical team. Consensus as to the role and predictive value of each of these tools is lacking and clinical practice regarding evaluation and selection of kidneys varies considerably.In this review, we seek to critically appraise the literature and evaluate the levels of evidence for tools used to assess deceased-donor kidneys. Although a plethora of appraisal tools exist, very few demonstrate desirable predictive power to be useful in clinical decision-making. Further research using large, well-designed prospective studies is urgently needed to advance this important field of transplantation science.

Strategies to increase the donor pool and access to kidney transplantation: an international perspective

In this position article, DESCARTES (Developing Education Science and Care for Renal Transplantation in European States) board members describe the current strategies aimed at expanding living and deceased donor kidney pools. The article focuses on the recent progress in desensitization and kidney paired exchange programmes and on the expanded criteria for the use of donor kidneys and organs from donors after circulatory death. It also highlights differences in policies and practices across different regions with special regard to European Union countries. Living donor kidney paired exchange, the deceased donor Acceptable Mismatch Programme and kidneys from donors after circulatory death are probably the most promising innovations for expanding kidney transplantation in Europe over the coming decade. To maximize success, an effort is needed to standardize transplant strategies, policies and legislation across European countries.

Pursuing Expanded Criteria Donors as Candidates for Kidney Donation after Circulatory Death

Of the 119 310 people on the national transplant waiting list, 97 280 people are waiting for kidneys. There simply are not enough organs to meet the demand. Recognizing that 64% of the people waiting for kidney transplants are at least 50 years old, this organ procurement organization embarked on a study to evaluate the potential of increasing the number of viable kidneys available for transplant by pursuing expanded criteria donors as donation after circulatory death (ECD/DCD) candidates. Pursuing ECD/DCD donors resulted in 24 additional donors (50–67 years old), 48 kidneys recovered, 30 kidneys transplanted into 26 recipients (44–74 years old), 7 kidneys placed for research, and 11 kidneys discarded, yielding an overall 62% transplant rate, 15% research rate, and 23% discard rate. The overall discard rate including all donors in all classifications during the study period was 13.1% (122 discards from 928 kidneys) compared with 12.6% (111 discards from 880 kidneys) when the study set was excluded. Although ECD/DCD donors still had the highest discard rates of all the groups, the 0.5% increase in the overall discard rate due to pursuing ECD/DCD kidneys was considered insignificant when compared with the benefit of the 30 additional kidneys transplanted. Including potential ECD/DCD patients in the donor pool increases the number of viable kidneys available for transplant without significantly increasing the overall kidney discard rates.

Pre-implant biopsy predicts outcome of single-kidney transplantation independent of clinical donor variables

BACKGROUND

Pre-implant biopsy findings account for the discard of many donor kidneys although their clinical value is not fully understood. We retrospectively investigated the predictive value of pre-implant histology, which in our center was obtained for protocol purposes, not for transplant decisions, on long-term allograft and recipient outcome after single-kidney transplantation.

METHODS

This single-center study included 628 consecutive adult recipients of 174 Expanded Criteria Donor (ECD) and 454 Standard Criteria Donor kidneys. Chronic donor organ injury was assessed applying a chronic lesion score differentiating between mild, moderate, and severe histologic organ injury based on the integration of glomerular, vascular, tubular, and interstitial lesions. Recipients were followed over a median time of 7.8 years.

RESULTS

Donor kidneys exhibiting mild or moderate chronic lesions yielded almost identical graft and recipient survival independent of ECD status or other clinical covariables (HR 1.20, 95% CI 0.83-1.74, P=0.326, and HR 1.27, 95% CI 0.83-1.95, P=0.274, respectively). However, if allograft injury was severe, occurring in 3% of transplanted kidneys, graft and recipient survival was significantly reduced (HR 3.13, 95% CI 1.61-6.07, P<0.001 and HR 2.42, 95% CI 1.16-5.04, P=0.005, respectively).

CONCLUSION

The results suggest that donor kidneys displaying moderate chronic injury can safely be transplanted as single kidneys, while organs displaying severe injury should be discarded. Thus, pre-implant biopsy might offer an effective approach to increase the utilization of renal donor organs, especially from ECD and donors with cerebrovascular accident as cause of death, and to improve overall graft outcome.

Glutathione S-transferase iso-enzymes in perfusate from pumped kidneys are associated with delayed graft function

Accurate and reliable assessment tools are needed in transplantation. The objective of this prospective, multi-center study was to determine the associations of the alpha and pi iso-enzymes of glutathione S-transferase (GST), measured from perfusate solution at the start and end (base and post) of kidney allograft machine perfusion, with subsequent delayed graft function (DGF). We also compared GST iso-enzyme perfusate levels from discarded versus transplanted kidneys. A total of 428 kidneys were linked to outcomes as recorded by the United Network of Organ Sharing. DGF, defined as any dialysis in the first week of transplant, occurred in 141 recipients (32%). Alpha- and pi-GST levels significantly increased during machine perfusion. The adjusted relative risks (95% confidence interval) of DGF with each log-unit increase in base and post pi-GST were 1.14 (1.0-1.3) and 1.36 (1.1-1.8), respectively. Alpha-GST was not independently associated with DGF. There were no significant differences in GST values between discarded and transplanted kidneys, though renal resistance was significantly higher in discarded kidneys. We found pi-GST at the end of machine perfusion to be independently associated with DGF. Further studies should elucidate the utility of GST for identifying injured kidneys with regard to organ allocation, discard and recipient management decisions.

Preimplant histologic acute tubular necrosis and allograft outcomes

BACKGROUND AND OBJECTIVES

The influence of deceased-donor AKI on post-transplant outcomes is poorly understood. The few published studies about deceased-donor preimplant biopsy have reported conflicting results regarding associations between AKI and recipient outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This multicenter study aimed to evaluate associations between deceased-donor biopsy reports of acute tubular necrosis (ATN) and delayed graft function (DGF), and secondarily for death-censored graft failure, first adjusting for the kidney donor risk index and then stratifying by donation after cardiac death (DCD) status.

RESULTS

Between March 2010 and April 2012, 651 kidneys (369 donors, 4 organ procurement organizations) were biopsied and subsequently transplanted, with ATN reported in 110 (17%). There were 262 recipients (40%) who experienced DGF and 38 (6%) who experienced graft failure. DGF occurred in 45% of kidneys with reported ATN compared with 39% without ATN (P=0.31) resulting in a relative risk (RR) of 1.13 (95% confidence interval [95% CI], 0.9 to 1.43) and a kidney donor risk index-adjusted RR of 1.11 (95% CI, 0.88 to 1.41). There was no significant difference in graft failure for kidneys with versus without ATN (8% versus 5%). In stratified analyses, the adjusted RR for DGF with ATN was 0.97 (95% CI, 0.7 to 1.34) for non-DCD kidneys and 1.59 (95% CI, 1.23 to 2.06) for DCD kidneys (P=0.02 for the interaction between ATN and DCD on the development of DGF).

CONCLUSIONS

Despite a modest association with DGF for DCD kidneys, this study reveals no significant associations overall between preimplant biopsy-reported ATN and the outcomes of DGF or graft failure. The potential benefit of more rigorous ATN reporting is unclear, but these findings provide little evidence to suggest that current ATN reports are useful for predicting graft outcomes or deciding to accept or reject allograft offers.

The role of procurement biopsies in acceptance decisions for kidneys retrieved for transplant

BACKGROUND AND OBJECTIVES

There is a shortage of kidneys for transplant, and many patients on the deceased donor kidney transplant waiting list would likely benefit from kidneys that are currently being discarded. In the United States, the most common reason given for discarding kidneys retrieved for transplant is procurement biopsy results. This study aimed to compare biopsy results from discarded kidneys with discard attributed to biopsy findings, with biopsy results from comparable kidneys that were successfully transplanted.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective, observational, case-control study, biopsy reports were examined from 83 kidneys discarded in 2010 due to biopsy findings (cases), 83 contralateral transplanted kidneys from the same donor (contralateral controls), and 83 deceased donors randomly matched to cases by donor risk profile (randomly matched controls). A second procurement biopsy was obtained in 64 of 332 kidneys (19.3%).

RESULTS

The quality of biopsy reports was low, with amounts of tubular atrophy, interstitial inflammation, arteriolar hyalinosis, and acute tubular necrosis often not indicated; 69% were wedge biopsies and 94% used frozen tissue. The correlation between first and second procurement biopsies was poor; only 25% of the variability (R(2)) in glomerulosclerosis was explained by biopsies being from the same kidney. The percentages of glomerulosclerosis overlapped substantially between cases, contralateral controls, and randomly matched controls: 17.1%±15.3%, 9.0%±6.6%, and 5.0%±5.9%, respectively. Of all biopsy findings, only glomerulosclerosis>20% was independently correlated with discard (cases versus contralateral controls; odds ratio, 15.09; 95% confidence interval, 2.47 to 92.41; P=0.003), suggesting that only this biopsy result was used in acceptance decisions. One-year graft survival was 79.5% and 90.7% in contralateral and randomly matched controls, respectively, versus 91.6% among all deceased donor transplants in the Scientific Registry of Transplant Recipients.

CONCLUSIONS

Routine use of biopsies could lead to unnecessary kidney discards.

The discard of deceased donor kidneys in the UK

It is essential to minimize the unnecessary discard of procured deceased donor kidneys, but information on discard rates and the extent to which discard can be avoided are limited. Analysis of the UK Transplant Registry revealed that the discard rate of procured deceased donor kidneys has increased from 5% in 2002-3 to 12% in 2011-12. A national offering system for hard-to-place kidneys was introduced in the UK in 2006 (the Declined Kidney Scheme), but just 13% of kidneys that were subsequently discarded until 2012 were offered through the scheme. In order to examine the appropriateness of discard, 20 consecutive discarded kidneys from 13 deceased donors were assessed to determine if surgeons agreed with the decision that they were not implantable. Donors had a median (range) age of 67 (31-80) yr. Kidneys had been offered to a median of 3 (1-12) centers before discard. Four (20%) of the discarded kidneys were thought to be usable, and nine (45%) were possibly usable. As a result of these findings, major changes to the UK deceased donor kidney offering system have been implemented, including simultaneous offering and broader entry criteria for hard-to-place kidneys. Organizational changes are necessary to improve utilization of deceased donor kidneys.

Kidneys at higher risk of discard: expanding the role of dual kidney transplantation

Half of the recovered expanded criteria donor (ECD) kidneys are discarded in the United States. A new kidney allocation system offers kidneys at higher risk of discard, Kidney Donor Profile Index (KDPI)>85%, to a wider geographic area to promote broader sharing and expedite utilization. Dual kidney transplantation (DKT) based on the KDPI is a potential option to streamline allocation of kidneys which otherwise would have been discarded. To assess the clinical utility of the KDPI in kidneys at higher risk of discard, we analyzed the OPTN/UNOS Registry that included the deceased donor kidneys recovered between 2002 and 2012. The primary outcomes were allograft survival, patient survival and discard rate based on different KDPI categories (<80%, 80-90% and >90%). Kidneys with KDPI>90% were associated with increased odds of discard (OR=1.99, 95% CI 1.74-2.29) compared to ones with KDPI<80%. DKTs of KDPI>90% were associated with lower overall allograft failure (HR=0.74, 95% CI 0.62-0.89) and better patient survival (HR=0.79, 95% CI 0.64-0.98) compared to single ECD kidneys with KDPI>90%. Kidneys at higher risk of discard may be offered in the up-front allocation system as a DKT. Further modeling and simulation studies are required to determine a reasonable KDPI cutoff percentile.

Oxygen consumption during oxygenated hypothermic perfusion as a measure of donor organ viability

Hypothermic machine perfusion (HMP) for the preservation of kidneys, recovered from extended criteria organ donors (ECDs), presents the opportunity for assessing ex vivo parameters that may have value in predicting postimplantation organ viability. Organ perfusion and vascular resistance are the parameters most frequently cited as the basis for the decision to use or discard a donor kidney. The limitation of these measures is emphasized by the observation that a significant percentage of ECD kidneys with poor perfusion parameters can provide life-sustaining function after transplantation. It has been suggested that whole organ oxygen consumption (OC) during oxygenated HMP may better reflect the proportion of viable tissue in the organ and more reliably predict posttransplant organ function. Our study correlates renal OC and renal vascular resistance (RVR) during oxygenated HMP with postpreservation glomerular filtration rates (GFRs) in rodent kidneys after 24 hours of oxygenated HMP. Kidneys from adult rodents were preserved for 24 hours using oxygenated HMP and static cold storage (SCS). During oxygenated HMP preservation, organ OC, renal organ flow rates, and RVR were serially measured. After the preservation period, organs were mounted onto a Langendorff device for warming to normal body temperature and measurement of GFR. Oxygen consumption and RVR during HMP were correlated with postpreservation GFR. Oxygen consumption during oxygenated HMP was significantly correlated (r2 = 0.871; p < 0.05) with postpreservation GFR, suggesting that higher OC predicts better postpreservation GFR. In contrast, RVR was poorly correlated with postpreservation GFR (r2 = 0.258; p = 0.199). Glomerular filtration rate in SCS kidneys was 0.002 ± 0.003 ml/min/g. We demonstrate that measurement of organ OC during oxygenated HMP may have significant value in predicting postpreservation organ function.

Access to renal transplantation for the elderly in the face of new allocation policy: a review of contemporary perspectives on "older" issues

The benefits of renal transplantation have been demonstrated to extend to the elderly. As a result, more seniors have been placed on the kidney transplant wait list and have received renal allografts in recent years. In June 2013 significant amendments to deceased donor kidney allocation policy were approved to be instituted in 2014 with the goal of increasing overall life years and graft years achieved compared to the current system. Going forward, it is conceivable that transplant centers may perceive a need to adjust practice patterns and modify evaluation and listing criteria for the elderly as the proportion of kidneys distributed to this segment of the wait list would potentially decrease under the new system, further increasing wait times. This review examines contemporary perspectives on access to transplantation for seniors and pertinent issues for this subgroup such as wait time, comorbidity, and evaluation and listing practices. Potential approaches to improve the evaluation of elderly patients being considered for transplant and to increase availability of expanded criteria donor (or higher kidney donor profile index) and living donor organ transplant opportunities while maintaining acceptable outcomes for seniors are explored.

Outcomes of adult dual kidney transplants by KDRI in the United States

UNOS guidelines provide inadequate discriminatory criteria for kidneys that should be transplanted as single (SKT) versus dual (DKT). We evaluated the utility of the kidney donor risk index (KDRI) to define kidneys with better outcomes when transplanted as dual. Using SRTR data from 1995 to 2010 of de novo KTX recipients of adult deceased-donor kidneys, we examined outcomes of SKT and DKT stratified by KDRI group ≤1.4 (n = 49 294), 1.41-1.8 (n = 15 674), 1.81-2.2 (n = 6523) and >2.2 (n = 2791). DKT of kidneys with KDRI >2.2 was associated with significantly better overall graft survival [adjusted hazard ratio (aHR) 0.83, 95% confidence interval (CI) 0.72-0.96] compared to single kidneys with KDRI >2.2. DKT was associated with significantly decreased odds of delayed graft function (top 2 KDRI categories) and significantly decreased odds of 1-year serum creatinine level >2 mg/dL (top 3 KDRI categories). Among SKT and DKT from KDRI >2.2 there were 16.1 and 13.9 graft losses per 100 patient follow-up years, respectively. KDRI >2.2 is a useful discriminatory cut-off for the determination of graft survival benefit with the use of DKT; however, the benefit of increased graft years was less than half of single kidneys from donors in the same KDRI range.

Impact of the pre-transplant histological score on 3-year graft outcomes of kidneys from marginal donors: a single-centre study

BACKGROUND

The reliability of kidney biopsy as the sole means for assessing kidneys from extended-criteria donors (ECDs) to be allocated to single or dual transplantation is still a matter of debate.

METHODS

We compared retrospectively 3 years graft survival and renal function in 44 recipients of a single kidney graft from a marginal donor with good renal function and a Karpinski histological score of ≤ 3 and 56 recipients of a single transplant with a Karpinski score of 4 or 5. The donors' and recipients' characteristics were compared by means of Wilcoxon's rank-sum test and Fisher's exact test, and survival was analysed using the log-rank test and Cox regression survival analysis.

RESULTS

The donors with the worse histological scores were slightly younger (68.0 ± 4.74 versus 71.3 ± 4.6 years, P < 0.01) and had a higher glomerular filtration rate (85.8 ± 28.2 versus 76.3 ± 26.53 mL/min, P = 0.013), but there was no difference in serum creatinine levels (0.83 ± 0.24 versus 0.85 ± 0.30 mg/dL, P = 0.381). Three years after transplantation, there was no difference between the two groups in terms of recipient serum creatinine levels (1.94 ± 0.69 versus 1.74 ± 0.49 mg/dL, P = 0.134), estimated glomerular filtration rate (eGFR, 45.6 ± 21.1 versus 51.7 ± 22.0 mL/min, P = 0.331) or the rates of graft loss (27.3 versus 35.7%, P = 0.47), delayed graft function or acute rejection.

CONCLUSIONS

In our experience, provided the donor has a normal renal function, a difference in the pre-transplant histological score of kidneys from marginal cadaveric donors do not have a significant influence on the outcome 3 years after transplantation. Our findings might represent a basis for designing a randomized controlled trial of using a higher histological score threshold for the DKT allocation of grafts from ECDs with a normal renal function.

Measurement of renovascular circulating volume during hypothermic organ perfusion

BACKGROUND

Kidney donation after cardiac death leads to vascular damage as a result of warm ischemia, affecting renovascular circulating volume. Novel ultrasound dilution techniques may be used to measure renovascular circulating volumes during hypothermic machine perfusion of donor kidneys.

METHODS

Renovascular circulating volumes of machine-perfused porcine kidneys were repeatedly measured by ultrasound dilution at different perfusion pressures (30, 40, 50, and 60 mm Hg), durations of perfusion (1 and 24 hr), and warm ischemia times (15 and 45 min). Validity of ultrasound dilution was assessed by comparing volume changes after clamping of renal artery branches.

RESULTS

Repeatability of ultrasound dilution measurements of renovascular circulating volumes was good (mean coefficient of variation, 7.6%). Renovascular circulating volumes significantly increased with higher perfusion pressures, remained constant over time, and significantly decreased with longer warm ischemia times. Changes in ultrasound dilution measurements after renal artery branch clamping did not correlate with changes in actual perfused volumes.

CONCLUSIONS

Ultrasound dilution is a reproducible method to assess renovascular circulating volumes in machine-perfused kidneys, which is susceptible to changes in warm ischemia times. Future studies should evaluate the value of renovascular volume in pretransplantation kidney viability testing.

Assessment of donor biopsies

PURPOSE OF REVIEW

To provide an up-to-date overview about the assessment of donor biopsies and to discuss the current problems and chances of preimplantation biopsies for transplant allocation with a focus on the technical work up and the histological variables scored.

RECENT FINDINGS

Preimplantation biopsy results are the major reason for discarding procured extended donor criteria kidneys in the USA. There is neither a consensus on the work up, nor the reporting of preimplantation donor biopsies, nor the importance of the biopsy findings in the process of allocation. The best available data have been collected in the context of single vs. double kidney transplantation. A clinical risk factor score may help to define kidneys when a preimplantation biopsy is warranted. Punch biopsies using a skin punch device appear to be a reasonable alternative for surgeons fearing needle biopsies.

SUMMARY

Donor biopsies are very useful as zero-hour biopsies establishing baseline information for comparison with subsequent transplant biopsies. As none of the histological variables and scores provides perfect prediction, preimplantation biopsy results have to be interpreted in the context of all available donor and recipient information.

Expanded Criteria Donors in Kidney Transplantation: The Role of Older Donors in a Setting of Older Recipients

Kidney transplantation (KT) is the therapy of choice for end-stage renal disease (ESRD). The ESRD population is aging and so are patients waiting for KT. New strategies have been made for increasing the donor and recipient pools, and as a consequence kidneys from older donors or donors with significant comorbidities, the so-called “expanded criteria donor” (ECD) kidneys, are used for transplantation. Although good outcomes have been achieved from ECD, several issues are still waiting for clarification and need to be discussed. The concept of age matching is accepted as a method to ameliorate utilization of these allografts, but an optimal and widely accepted strategy is still not defined. The development of machine perfusion and the dual kidney transplantation are techniques which further improve the outcome of transplants from ECD, but the described experiences are scarce or coming from small single institutional reports. Also due to age-related immune dysfunction and associated comorbidities, the elderly recipients are more susceptible to immunosuppression related complications (e.g., infections and malignancy), although a widely accepted and validated immunosuppressive regimen is still lacking. In this paper, we review the issues related to KT employing allografts from marginal donors with a particular interest for the elderly patients.

Machine perfusion viability testing

PURPOSE OF REVIEW

Pretransplant assessment of kidney graft viability may help clinicians to decide whether to accept or discard a kidney for transplantation. With the increasing demand for donor kidneys and the increased use of marginal kidneys, the need of viability markers has increased to pursue superior transplant outcomes. Hypothermic machine perfusion (HMP) provides the theoretical opportunity to assess the viability of donor kidneys. We discuss the novel developments in viability testing during HMP and address the future prospects.

RECENT FINDINGS

HMP viability testing has focused on the analysis of machine perfusion parameters and perfusate biomarkers. Renal resistance and the biomarkers lactate dehydrogenase, aspartate transaminase, glutathione-S-transferase, N-acetyl-β-D-glucosaminidase, heart-type fatty acid binding protein, lipid peroxidation products, redox-active iron and IL-18 are correlated with transplant outcome in terms of development of delayed graft function or graft survival. However, they all lack adequate predictive value for transplant outcome. New techniques including contrast-enhanced ultrasound, three-dimensional ultrasound and magnetic resonance spectrometry are promising methods to test kidney viability during HMP, but their value has to be established. The introduction of normothermic machine perfusion offers other promising opportunities for viability testing.

SUMMARY

Machine perfusion characteristics and perfusate biomarkers have been extensively studied. They often correlate with the transplant outcome, but the present viability tests are not reliable predictors of transplant outcome. New developments in kidney graft viability assessment are necessary to have a chance of being clinically useful in the future.

Deceased organ donation consent rates among racial and ethnic minorities and older potential donors

OBJECTIVES

We sought to assess consent rates for organ donation from potential brain-dead donors, and to identify factors associated with variation in consent for donation that could guide the development of targeted interventions to increase organ consent rates.

DESIGN, SETTING, AND SUBJECTS

We used data provided by the Organ Procurement and Transplantation Network to analyze the 35,823 organ procurement organization-reported eligible deaths (potential brain-dead donors ≤ 70 yr of age) from January 1, 2008, to October 31, 2011.

MEASUREMENTS AND MAIN RESULTS

Excluding cases where donation authorization was based on prior patient documentation (e.g., donor registry), consent was obtained on 21,601 (68.9%), not obtained on 8,727 (27.8%), and not requested on 1,080 (3.4%) eligible deaths. There were substantial differences in consent rates among racial/ethnic groups (77.0% in whites, 67.5% in Hispanics, 54.9% in blacks, and 48.1% in Asians) and organ procurement organizations (median [interquartile range]: 72.4% [67.5-87.3]). In generalized estimating equation models, with whites and patients ages 18-39 yr as the respective reference groups, consent for donation was less likely to be obtained among Hispanics (odds ratio 0.54; 95% confidence interval 0.44-0.65), blacks (odds ratio 0.35; 95% confidence interval 0.31-0.39), Asians (odds ratio 0.31; 95% confidence interval 0.25-0.37), and eligible donors ages 55-64 (odds ratio 0.72; 95% confidence interval 0.67-0.77), and ≥ 65 yr (odds ratio 0.58; 95% confidence interval 0.52-0.64).

CONCLUSIONS

In presenting the first published analyses of consent rates among all eligible deaths, this study confirms smaller and regional studies that showed significant differences in consent rates between whites and racial/ethnic minorities (blacks, Hispanics, and Asians). The study also identifies considerable variation in consent rates between age groups and between organ procurement organizations. Critical care physicians are usually the front-line providers for potential brain-dead donors and their next-of-kin, and these data highlight the need for further research to identify the causes of variation in consent rates and mechanisms to increase rates where appropriate.

Evaluating safety and efficacy of rabbit antithymocyte globulin induction in elderly kidney transplant recipients

OBJECTIVES

The optimal immunosuppression regimen for elderly kidney transplant recipients is poorly defined. We sought to evaluate the short-term efficacy and safety of thymoglobulin in geriatric recipients of deceased-donor kidneys.

MATERIALS AND METHODS

A single-center, retrospective analysis was undertaken between elderly (≥ 65 years) (n=137) and nonelderly (n=276) kidney transplant recipients who received rabbit antithymocyte globulin induction and calcineurin inhibitor, mycophenolic acid, and prednisone maintenance.

RESULTS

The mean age was 70 versus 52 years. Fewer elderly patients had an earlier transplant or panel reactive antibodies > 20%, but had more machine perfused, older, and extended criteria donor kidneys. Elderly patients received lower rabbit antithymocyte globulin (5.4 vs 5.6 mg/kg; P = .04) and initial mycophenolic acid doses (1620 vs 1774 mg; P = .002), and experienced less delayed graft function (31.1% vs 50.0%; P < .001). Death-censored graft survival and graft function at 3 years and biopsy-proven acute rejection at 1 year were comparable; however, there was lower 3-year patient survival in elderly patients. Donor age was the only factor associated with reduced patient survival. Rates of malignancy, infection, or thrombocytopenia were similar; however, leukopenia occurred less frequently in elderly patients (11.7% vs 19.9%; P = .038).

CONCLUSIONS

Elderly kidney transplant recipients receiving rabbit antithymocyte globulin did not experience different short-term graft survival, graft function or rates of infection, malignancy or hematologic adverse reactions than did nonelderly patients; they experienced fewer episodes of delayed graft function, but had lower 3-year patient survival.

Comparing molecular assessment of implantation biopsies with histologic and demographic risk assessment

We hypothesized that measurement of previously defined acute kidney injury-induced transcripts at the time of implantation would add a new dimension to existing methods based on donor factors, histology and recipient factors. We analyzed microarray results from implantation biopsies taken after reperfusion from 70 kidneys from 53 deceased donors. We used two definitions of early dysfunction: serum creatinine > 265 umol/L at day 7 posttransplant; and dialysis in the first week. The strongest correlate with early dysfunction was the mean expression of 30 injury transcripts. Older donor and recipient age were associated with early dysfunction, but histologic lesions were not. Prediction was best when the injury transcript expression was combined with donor or recipient age, particularly in standard criteria donors. In contrast, although extended criteria donor kidneys had a high risk of early dysfunction, no variables tested, including injury transcripts, predicted risk significantly, probably because these kidneys were allocated preferentially to old, high risk recipients. The injury transcripts did not predict late function, which was mainly associated with donor age. Thus, measurement of injury-induced transcripts at the time of implantation improves the prediction of early kidney dysfunction, but risk prediction may fail when old kidneys are transplanted into old recipients.

Effect of increased pressure during pulsatile pump perfusion of deceased donor kidneys in transplantation

INTRODUCTION

Pulsatile pump perfusion of potential kidneys for transplantation is known to decrease the rate of delayed graft function (DGF) and improve their 1-year survival. Flow and resistance parameters are often used to determine the suitability of kidneys for transplantation. Kidneys with low flow rates are often subjected to higher pressures to improve flow. This study evaluated the effect of higher pump pressures on posttransplant renal function.

METHODS

We performed a retrospective analysis of 73 deceased donor kidneys preserved using pump perfusion (LifePort) at our center between May 2006 and September 2009. We calculated the mean pump pressure (MP) for the duration of perfusion of each kidney, using systolic pressure (SP) and diastolic pressure (DP) readings with the following formula: (MP = DP + 1/3 (SP - DP). The kidneys were divided into a low (LP; n = 49) and a high-pressure group (HP; n = 24) based on a MP cutoff value of 23 mm Hg. The two groups were then compared for differences in perfusion dynamics and primary endpoints including DGF and 1-year graft survival. Statistical analysis was performed using paired Student t test and chi-square analysis.

RESULTS

The two groups were comparable for donor age, extended criteria, sensitization, and cold ischemic times. They differed significantly in higher initial (0.65 ± 0.4 versus 0.4 ± 0.2, P = .01), average (0.25 ± 0.08 versus 0.18 ± 0.06, P = .0006), and terminal resistance (0.21 ± 0.07 versus 0.17 ± 0.06, P = .008) of HP versus LP kidneys. Flow rates were comparable between the two groups. DGF was higher in HP kidneys (75% versus 40%, P = .006) with similar 1-year graft survival (87.5% versus 89%, P = .7).

CONCLUSIONS

Perfusate flow through a kidney can be improved by increasing pressure settings to overcome elevated resistance. This maneuver was not associated with a lower rate of DGF after transplantation. One-year graft survival remained unaffected.