Import kidney transplants from nonmandatory share deceased donors: characteristics, distribution and outcomes

Kidney Transplant Outcomes after Prolonged Delayed Graft Function

Background: The protracted recovery of renal function may be an actionable marker of post-transplant adverse events, but a paucity of data are available to determine if the duration of graft recovery serves to stratify risk. Materials and Methods: Single-center data of adult-isolated deceased-donor kidney transplant (KTX) recipients between 1 July 2015 and 31 December 2018 were stratified by delayed graft function (DGF) duration, defined as time to serum creatinine < 3.0 mg/dL. Results: Of 355 kidney transplants, the time to creatinine < 3.0 mg/dL was 0−3 days among 96 cases (DGF ≤ 3), 4−10 days among 85 cases (DGF4-10), 11−20 days among 93 cases (DGF11-20), and ≥21 days for 81 cases (DGF ≥ 21). DGF ≥ 21 recipients were significantly more likely to be male, non-sensitized, and receive kidneys from donors that were older, with donation after circulatory death, non-mandatory share, hypertensive, higher KDPI, higher terminal creatinine, and longer cold and warm ischemia time. On multivariate analysis, DGF ≥ 21 was associated with a 5.73-fold increased odds of 12-month eGFR < 40 mL/min compared to DGF ≤ 3. Lesser degrees of DGF had similar outcomes. Conclusions: Prolonged DGF lasting over 20 days signifies a substantially higher risk for reduced eGFR at 1 year compared to lesser degrees of DGF, thus serving as a threshold indicator of increased risk.

Hardest-to-place kidney transplant outcomes in the United States

The outcomes of hardest-to-place kidney transplants-accepted last in the entire match run after being refused by previous centers-are unclear, potentially translating to risk aversion and unnecessary organ discard. We aimed to determine the outcomes of hardest-to-place kidney transplants and whether the organ acceptance position on the match run sufficiently captures the risk. This is a cohort study of the United Network for Organ Sharing data of all adult kidney-only transplant recipients from deceased donors between 2007 and 2018. Multiple regression models assessed delayed graft function, graft survival, and patient survival stratified by share type: local versus shared kidney acceptance position scaled by tertile. Among 127 028 kidney transplant recipients, 92 855 received local kidneys. The remaining received shared kidneys at sequence number 1-4 (n = 12 322), 5-164 (n = 10 485) and >164 (n = 11 366). Hardest-to-place kidneys, defined as the latest acceptance group in the match-run, were associated with delayed graft function (adjusted odds ratio 1.83, 95% confidence interval [CI] 1.74-1.92) and all-cause allograft failure (adjusted hazard ratio [aHR] 1.11, 95% CI 1.04-1.17). Results of this IRB-approved study were robust to the exclusion of operational allocation bypass and mandatory shares. The hardest-to-place kidneys accepted later in the match run were associated with higher graft failure and delayed graft function.

Association of Dialysis Duration With Outcomes After Kidney Transplantation in the Setting of Long Cold Ischemia Time

Background

There is no mechanism that matches hard-to-place kidneys with the most appropriate candidate. Thus, unwanted kidney offers are typically to recipients with long renal replacement time (vintage) which is a strong risk factor for mortality and graft failure, and in combination with prolonged cold ischemia time (CIT), may promote interactive effects on outcomes.

Methods

Consecutive adult isolated kidney transplants between October 2015 and December 2017 were stratified by vintage younger than 1 year and CIT longer than 30 hours.

Results

Long (n = 169) relative to short (n = 93) vintage recipients were significantly more likely to be younger (32.2 years vs 56.9 years, P = 0.02), black race (40.8% vs 18.3%, P = 0.02), have higher estimated posttransplant survival (52.6 vs 42.0, P = 0.04), and have a comorbid condition (45.6% vs 30.1%, P = 0.02); they were less likely to receive a donation after circulatory death kidney (27.8% vs 39.8%, P = 0.05). Long vintage was significantly associated with length of stay longer than 4 days (45.5% vs 30.1%, P = 0.02), and 30-day readmission (37.3% vs 22.6%, P = 0.02) but not additional operations (17.8% vs 15.1%, P = 0.58), short-term patient mortality (3.0% vs 2.2%, P = 0.70), or overall graft survival (P = 0.23). On multivariate logistic regression, long vintage remained an independent risk factor for 30-day readmission (adjusted odds ratio, 1.92; 95% confidence interval, 1.06-3.47); however, there was no interaction of vintage and CIT for this outcome (P = 0.84).

Conclusions

Readmission is significantly associated with pretransplant dialysis duration; however, CIT is not a modifying factor for this outcome.

Hard-to-place kidney offers: Donor- and system-level predictors of discard

Understanding risk factors for deceased-donor kidney nontransplantation is important since discard rates remain high. We analyzed DonorNet^® data of consecutive deceased-donor nonmandatory share primary kidney-only offers to adult candidates at our center and beyond between July 1, 2015 and March 31, 2016 for donor- and system-level risk factors of discard, defined as nontransplantation at our or subsequent transplant centers. Exclusions were hepatitis C virus/hepatitis B virus core antibody status, blood type AB, and donor <1 year based on low candidate waitlist size. Of 456 individual kidney offers, from 296 donors, 73% were discarded. Most were national (93%) offers from Kidney Donor Profile Index 35-85% (n = 233) or >85% (n = 208) donors late in the allocation sequence with prior refusals logged for numerous candidates. On multivariate regression, factors significantly associated with discard were donor cerebrovascular accident (adjusted odds ratio [aOR]: 3.32), cancer transmission concern (aOR: 6.5), renal artery luminal compromise (aOR: 3.97), biopsy score ≥3 (aOR: 5.09), 2-hour pump resistive index >0.4 (aOR: 3.27), absence of pump (aOR: 2.58), nonspecific kidney abnormality (aOR: 2.76), increasing offer cold ischemia time category 11-15, 16-20, and >21 hours (aOR: 2.07, 2.33, 2.82), nighttime notification (aOR: 2.19), and neither kidney placed at time of offer (aOR: 2.74). Many traditional determinants of discard lack discriminatory value when granular factors are assessed. System-level factors also influence discard and warrant further study.

Kidney allograft offers: Predictors of turndown and the impact of late organ acceptance on allograft survival

There is growing interest in understanding patterns of organ acceptance and reducing discard. Little is known about how donor factors, timing of procurement, and geographic location affect organ offer decisions. We performed a retrospective cohort study of 47 563 deceased donor kidney match-runs from 2007 to 2013. Several characteristics unrelated to allograft quality were independently associated with later acceptance in the match-run: Public Health Service increased-risk donor status (adjusted odds ratio [aOR] 2.49, 95% confidence interval [CI] 2.29-2.69), holiday or weekend procurement (aOR 1.11, 95% CI 1.07-1.16), shorter donor stature (aOR 1.53 for <150 cm vs reference >180 cm, 95% CI 1.28-1.94), and procurement in an area with higher intensity of market competition (aOR 1.71, 95% CI 1.62-1.78) and with the longest waiting times (aOR 1.41, 95% CI 1.34-1.49). Later acceptance in the match-run was associated with delayed graft function but not all-cause allograft failure (adjusted hazard ratio 1.01, 95% CI 0.96-1.07). Study limitations include a lack of match-run data for discarded organs and the possibility of sequence inaccuracies for some nonlocal matches. Interventions are needed to reduce turndowns of viable organs, especially when decisions are driven by infectious risk, weekend or holiday procurement, geography, or other donor characteristics unrelated to allograft quality.

Analysis of local versus imported expanded criteria donor kidneys: A single-center experience with 497 ECD kidney transplants

BACKGROUND

The value of importing expanded criteria donor (ECD) kidneys is uncertain.

METHODS

We retrospectively reviewed our single-center experience with ECD kidney transplants (KT).

RESULTS

Over 12.8 years, we performed 497 ECD KTs including 247 local and 250 imported from other donor service areas. The import ECD group had more donors (16% vs 9%) ≥ age 70, more zero human leukocyte antigen mismatches (14% vs 2%), more KTs with a cold ischemia time >30 hours (46% vs 19%), and fewer kidneys managed with pump preservation (78% vs 92%, all P≤.05) compared to the local ECD group. Mean Kidney Donor Profile Index were 80% import vs 84% local. With a mean follow-up of 55 months, actual patient and graft survival rates were 71% and 58% in import vs 76% and 58% in local ECD KTs, respectively. Death-censored graft survival rates were 70% in import vs 69% in local ECD KTs. Delayed graft function occurred in 28% import vs 23% local ECD KTs (P=NS) whereas the incidence of primary nonfunction was slightly higher with import ECD kidneys (4.8% vs 2.4%, P=.23).

CONCLUSIONS

Midterm outcomes are remarkably similar for import vs local ECD KTs, suggesting that broader sharing of ECD kidneys may improve utilization without compromising outcomes.

Impact of Cold Ischemia Time in Kidney Transplants From Donation After Circulatory Death Donors

BACKGROUND

Deceased-donor kidneys are exposed to ischemic events from donor instability during the process of donation after circulatory death (DCD). Clinicians may be reluctant to transplant DCD kidneys with prolonged cold ischemia time (CIT) for fear of an additional deleterious effect.

METHODS

We performed a retrospective cohort study examining US registry data between 1998 and 2013 of adult first-time kidney-only recipients of paired kidneys (derived from the same donor transplanted into different recipients) from DCD donors.

RESULTS

On multivariable analysis, death-censored graft survival (DCGS) was comparable between recipients of kidneys with higher CIT relative to paired donor recipients with lower CIT when the CIT difference was 1 hour or longer (adjusted hazard ratio, [aHR], 1.02; 95% confidence interval [CI], 0.88-1.17; n = 6276), 5 hours or longer (aHR, 0.98; 95% CI, 0.80-1.19; n = 3130), 10 hours or longer (aHR, 1.15; 95% CI, 0.82-1.60; n = 1124) or 15 hours (aHR, 1.15; 95% CI, 0.66-1.99; n = 498). There was a higher rate of primary non function in the long CIT groups for delta 1 hour or longer (0.89% vs 1.63%; P = 0.006), 5 hours (1.09% vs 1.67%, P = 0.13); 10 hours (0.53% vs 1.78%; P = 0.03), and 15 hours (0.40% vs 1.61%; P = 0.18), respectively. Between each of the 4 delta CIT levels of shorter and longer CIT, there was a significantly and incrementally higher rate of delayed graft function in the long CIT groups for delta 1 hour or longer (37.3% vs 41.7%; P < 0.001), 5 hours (35.9% vs 42.7%; P < 0.001), 10 hours (29.4% vs 44.2%, P < 0.001), and 15 hours (29.6% vs 46.1%, P < 0.001), respectively. Overall patient survival was comparable with delta CITs of 1 hour or longer (aHR, 0.96; 95% CI, 0.84-1.08), 5 hours (aHR, 1.01; 95% CI, 0.85-1.20), and 15 hours (aHR, 1.27; 95% CI, 0.79-2.06) but not 10 hours (aHR, 1.47; 95% CI, 1.09-1.98).

CONCLUSIONS

These results suggest that in the setting of a prior ischemic donor event, prolonged CIT has limited bearing on long-term outcomes.

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.

Purinergic signaling and blood vessels in health and disease

Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.

The association of center performance evaluations and kidney transplant volume in the United States

Report cards evaluating transplant center performance have received significant attention in recent years corresponding with the Centers for Medicare and Medicaid Services issue of the 2007 Conditions of Participation. Our primary aim was to evaluate the association of report card evaluations with transplant center volume. We utilized data from the Scientific Registry of Transplant Recipients (SRTR) along with six consecutive program-specific reports from January 2007 to July 2009 for adult kidney transplant centers. Among 203 centers, 46 (23%) were low performing (LP) with statistically significantly lower than expected 1-year graft or patient survival at least once during the study period. Among LP centers, there was a mean decline in transplant volume of 22.4 cases compared to a mean increase of 7.8 transplants among other centers (p = 0.001). Changes in volume between LP and other centers were significant for living, standard and expanded criteria deceased donor (ECD) transplants. LPs had a reduction in use of donors with extended cold ischemia time (p = 0.04) and private pay recipients (p = 0.03). Centers without low performance evaluations were more likely to increase the proportion of overall transplants that were ECDs relative to other centers (p = 0.04). Findings indicate a significant association between reduced kidney transplant volume and low performance report card evaluations.

Impact of cold ischemia time on graft survival among ECD transplant recipients: a paired kidney analysis

Delays in expanded criteria donor (ECD) kidney placement increases cold ischemia times (CIT) potentially leading to discard. The effect of increased CIT on ECD kidney transplant outcomes is unknown. We evaluated paired ECD kidneys (derived from the same donor transplanted to different recipients) from the SRTR registry transplanted between 1995 and 2009 (n = 17,514). To test the effect of CIT, we excluded paired transplants with the same CIT (n = 3286). Of 14,230 recipients (7115 donors) the median difference in CIT was 5 h (Q1 = 3 h, Q3 = 9 h). Delayed graft function (DGF) was significantly more likely between pairs with greater CIT (35% vs. 31%, p < 0.001) including substantially higher rates for CIT differences ≥ 15 h (42%). Overall graft loss was not significantly different between recipients with higher CIT relative to paired donor recipients with lower CIT (p = 0.47) or for pairs with differences of 1-3 h (p = 0.90), 4-9 h (p = 0.41), 10-14 h (p = 0.36) or ≥ 15 h (p = 0.10). Results were consistent in multivariable models adjusted for recipient factors. Although increasing cold ischemia time is a risk factor for DGF among ECD kidney transplants, there is no effect on graft survival which may suggest an important utility for donor kidneys that may not currently be considered viable.

Influence of CIT-induced DGF on kidney transplant outcomes

Increased cold ischemia time (CIT) predisposes to delayed graft function (DGF). DGF is considered a risk factor for graft failure after kidney transplantation, but DGF has multiple etiologies. To analyze the risk of CIT-induced DGF on graft survival, we evaluated paired deceased-donor kidneys (derived from the same donor transplanted to different recipients) in which one donor resulted in DGF and the other did not, using national Scientific Registry of Transplant Recipients data between 2000 and 2009. Of 54 565 kidney donors, 15 833 were excluded for mate kidney non-transplantation, 27 340 because both or neither kidney developed DGF and 2310 for same/unknown CIT. The remaining 9082 donors (18 164 recipients) were analyzed. The adjusted odds (aOR) of DGF were significantly higher when CIT was longer by ≥ 1 h (aOR 1.81, 95% CI 1.7-2.0), ≥ 5 h (aOR 2.5, 95% CI 2.3-2.9), ≥ 10 h (aOR 3.3, 95% CI 2.7-2.9) and ≥ 15 h (aOR 4.4, 95% CI 3.4-5.8) compared to shorter CIT transplants. In the multivariable models adjusted for recipient characteristics, graft survival between paired donor transplants, with and without DGF, were similar. These results suggest that DGF, specifically induced by prolonged CIT, has limited bearing on long-term outcomes, which may have important implications for kidney utilization.