The landscape of international living kidney donation in the United States

In the United States, kidney donation from international (noncitizen/nonresident) living kidney donors (LKDs) is permitted; however, given the heterogeneity of healthcare systems, concerns remain regarding the international LKD practice and recipient outcomes. We studied a US cohort of 102 315 LKD transplants from 2000‐2016, including 2088 international LKDs, as reported to the Organ Procurement and Transplantation Network. International LKDs were more tightly clustered among a small number of centers than domestic LKDs (Gini coefficient 0.76 vs 0.58, P < .001). Compared with domestic LKDs, international LKDs were more often young, male, Hispanic or Asian, and biologically related to their recipient (P < .001). Policy‐compliant donor follow‐up was substantially lower for international LKDs at 6, 12, and 24 months postnephrectomy (2015 cohort: 45%, 33%, 36% vs 76%, 71%, 70% for domestic LKDs, P < .001). Among international LKDs, Hispanic (aOR = _0.230.36_0.56, P < .001) and biologically related (aOR = _0.390.59_0.89, P < .01) donors were more compliant in donor follow‐up than white and unrelated donors. Recipients of international living donor kidney transplant (LDKT) had similar graft failure (aHR = _0.780.89_1.02, P = .1) but lower mortality (aHR = _0.530.62_0.72, P < .001) compared with the recipients of domestic LDKT after adjusting for recipient, transplant, and donor factors. International LKDs may provide an alternative opportunity for living donation. However, efforts to improve international LKD follow‐up and engagement are warranted.     

A donor risk index for graft loss in pediatric living donor kidney transplantation

Pediatric kidney transplant candidates often have multiple potential living donors (LDs); no evidence‐based tool exists to compare potential LDs, or to decide between marginal LDs and deceased donor (DD) kidney transplantation (KT). We developed a pediatric living kidney donor profile index (P‐LKDPI) on the same scale as the DD KDPI by using Cox regression to model the risk of all‐cause graft loss as a function of living donor characteristics and DD KDPI. HLA‐B mismatch (adjusted hazard ratio [aHR] per mismatch = _1.041.27_1.55), HLA‐DR mismatch (aHR per mismatch = _1.021.23_1.49), ABO incompatibility (aHR = _1.203.26_8.81), donor systolic blood pressure (aHR per 10 mm Hg = _1.011.07_1.18), and donor estimated GFR (eGFR; aHR per 10 mL/min/1.73 m² = _0.880.94_0.99) were associated with graft loss after LDKT. Median (interquartile range [IQR]) P‐LKDPI was ?25 (?56 to 12). 68% of donors had P‐LKDPI <0 (less risk than any DD kidney) and 25% of donors had P‐LKDPI >14 (more risk than median DD kidney among pediatric KT recipients during the study period). Strata of LDKT recipients of kidneys with higher P‐LKDPI had a higher cumulative incidence of graft loss (39% at 10 years for P‐LDKPI ≥20, 28% for 20> P‐LKDPI ≥?20, 23% for ?20 > P‐LKDPI ≥?60, 19% for P‐LKDPI <?60 [log rank P < .001]). The P‐LKDPI can aid in organ selection for pediatric KT recipients by allowing comparison of potential LD and DD kidneys.     

Use of expanded-criteria donors and > 85 KDPI kidneys for pediatric kidney transplantation in the United States

Pediatric kidney transplant outcomes associated with expanded-criteria donors (ECD) and high Kidney Donor Profile Index (KDPI) kidneys are unknown. We reviewed the Scientific Registry of Transplant Recipients data from 1987-2017 to identify 96 ECD and 92 > 85 KDPI kidney recipients (<18 years). Using propensity scores, we created comparison groups of 375 non-ECD and 357 ≤ 85 KDPI recipients for comparisons with ECD and > 85 KDPI transplants, respectively. We used Cox regression for patient/graft survival and sequential Cox approach for survival benefit of ECD and > 85 KDPI transplantationvs remaining on the waitlist. After adjustment, ECD recipients were at significantly increased risk of graft failure (adjusted hazard ratio [aHR] = 1.6; P = .001) but not of mortality (aHR = 1.33; P = .15) compared with non-ECD recipients. We observed no survival benefit of ECD transplants vs remaining on the waitlist (aHR = 1.05; P = .83). We found no significant difference in graft failure (aHR = 1.27; P = .12) and mortality (aHR = 1.41; P = .13) risks between > 85 KDPI and ≤ 85 KDPI recipients. However, > 85 KDPI transplants were associated with a survival benefit vs remaining on the waitlist (aHR = 0.41; P = .01). ECD transplantation in children is associated with a high graft loss risk and no survival benefit, whereas > 85 KDPI transplantation is associated with a survival benefit for children vs remaining on the waitlist.     

The benefit to waitlist patients in a national paired kidney exchange program: Exploring characteristics of chain end living donor transplants

Nondirected kidney donors can initiate living donor chains that end to patients on the waitlist. We compared 749 National Kidney Registry (NKR) waitlist chain end transplants to other transplants from the NKR and the Scientific Registry of Transplant Recipients between February 2008 and September 2020. Compared to other NKR recipients, chain end recipients were more often older (53 vs. 52 years), black (32% vs. 15%), publicly insured (71% vs. 46%), and spent longer on dialysis (3.0 vs. 1.0 years). Similar differences were noted between chain end recipients and non-NKR living donor recipients. Black patients received chain end kidneys at a rate approaching that of deceased donor kidneys (32% vs. 34%). Chain end donors were older (52 vs. 44 years) with slightly lower glomerular filtration rates (93 vs. 98 ml/min/1.73 m²) than other NKR donors. Chain end recipients had elevated risk of graft failure and mortality compared to control living donor recipients (both p < .01) but lower graft failure (p = .03) and mortality (p < .001) compared to deceased donor recipients. Sharing nondirected donors among a multicenter network may improve the diversity of waitlist patients who benefit from living donation.     

Temporal trends in utilization and outcomes of steatotic donor livers in the United States

Steatotic donor livers (SDLs) (macrosteatosis ≥30%) represent a possible donor pool expansion, but are frequently discarded due to a historical association with mortality and graft loss. However, changes in recipient/donor demographics, allocation policy, and clinical protocols might have altered utilization and outcomes of SDLs. We used Scientific Registry of Transplant Recipients data from 2005 to 2017 and adjusted multilevel regression to quantify temporal trends in discard rates (logistic) and posttransplant outcomes (Cox) of SDLs, accounting for Organ Procurement Organization–level variation. Of 4346 recovered SDLs, 58.0% were discarded in 2005, versus only 43.1% in 2017 (P < .001). SDLs were always substantially more likely discarded versus non‐SDLs, although this difference decreased over time (adjusted odds ratio in 2005‐2007:_13.1515.28_17.74; 2008‐2011:_11.7713.41_15.29; 2012‐2014:_9.8711.37_13.10; 2015‐2017:_7.798.89_10.15, P < .001 for all). Conversely, posttransplant outcomes of recipients of SDLs improved over time: recipients of SDLs from 2012 to 2017 had 46% lower risk of mortality (adjusted hazard ratio [aHR]: _0.430.54_0.68, P < .001) and 47% lower risk of graft loss (aHR: _0.420.53_0.67, P < .001) compared to 2005 to 2011. In fact, in 2012 to 2017, recipients of SDLs had equivalent mortality (aHR: _0.901.04_1.21, P = .6) and graft loss (aHR: _0.901.04_1.20, P = .6) to recipients of non‐SDLs. Increasing utilization of SDLs might be a reasonable strategy to expand the donor pool.     

The “oldest and coldest” shipped living donor kidneys transplanted through kidney paired donation

To date, thousands of living donor kidneys have been shipped through kidney paired donation (KPD). To expand on this growing segment of living donor transplantation, we evaluated the effect of advanced age donation (“oldest kidneys”) and prolonged cold ischemia time (“coldest kidneys”) on graft function and survival using the National Kidney Registry database from February 2008 to May 2018. Donors were stratified by age at time of donation (<65 or ≥65 years) and kidneys were stratified by cold ischemia time (<16 or ≥16 hours). We evaluated delayed graft function and death‐censored graft failure (DCGF) for up to seven posttransplant years. Of the 2363 shipped living donor kidney transplants, 4.1% of donors were ≥65 years and 6.0% of transplanted kidneys had cold ischemia times ≥16 hours. Delayed graft function and DCGF occurred in 5.2% and 4.7% of cases. There were no significant associations between delayed graft function and donor age (P = .947) or cold ischemia (P = .532). Donor age and cold ischemia time were not predictive of delayed graft function (OR = 0.86,1.20; P = .8, .6) or DCGF (HR = 1.38,0.35, P = .5, .1). These findings may alleviate concerns surrounding the utilization of kidneys from older donors or those originating from distant transplant centers.     

Quantifying infection risks in incompatible living donor kidney transplant recipients

Desensitization has enabled incompatible living donor kidney transplantation (ILDKT) across HLA/ABO barriers, but added immunomodulation might put patients at increased risk of infections. We studied 475 recipients from our center from 2010 to 2015, categorized by desensitization intensity: none/compatible (n = 260), low (0-4 plasmaphereses, n = 47), moderate (5-9, n = 74), and high (≥10, n = 94). The 1-year cumulative incidence of infection was 50.1%, 49.8%, 66.0%, and 73.5% for recipients who received none, low, moderate, and high-intensity desensitization (P < .001). The most common infections were UTI (33.5% of ILDKT vs. 21.5% compatible), opportunistic (21.9% vs. 10.8%), and bloodstream (19.1% vs. 5.4%) (P < .001). In weighted models, a trend toward increased risk was seen in low (wIRR = _0.771.40_2.56,P = .3) and moderately (wIRR = _0.881.35_2.06,P = .2) desensitized recipients, with a statistically significant 2.22-fold (wIRR = _1.332.22_3.72,P = .002) increased risk in highly desensitized recipients. Recipients with ≥4 infections were at higher risk of prolonged hospitalization (wIRR = _2.623.57_4.88, P < .001) and death-censored graft loss (wHR = _1.154.01_13.95,P = .03). Post–KT infections are more common in desensitized ILDKT recipients. A subset of highly desensitized patients is at ultra-high risk for infections. Strategies should be designed to protect patients from the morbidity of recurrent infections, and to extend the survival benefit of ILDKT across the spectrum of recipients.     

Kidney transplant outcomes associated with the use of increased risk donors in children

Increased risk donors (IRDs) may inadvertently transmit blood‐borne viruses to organ recipients through transplant. Rates of IRD kidney transplants in children and the associated outcomes are unknown. We used the Scientific Registry of Transplant Recipients to identify pediatric deceased donor kidney transplants that were performed in the United States between January 1, 2005 and December 31, 2015. We used the Cox regression analysis to compare patient and graft survival between IRD and non‐IRD recipients, and a sequential Cox approach to evaluate survival benefit after IRD transplants compared with remaining on the waitlist and never accepting an IRD kidney. We studied 328 recipients with and 4850 without IRD transplants. The annual IRD transplant rates ranged from 3.4% to 13.2%. IRDs were more likely to be male (P = .04), black (P < .001), and die from head trauma (P = .006). IRD recipients had higher mean cPRA (0.085 vs 0.065, P = .02). After multivariate adjustment, patient survival after IRD transplants was significantly higher compared with remaining on the waitlist (adjusted hazard ratio [aHR]: 0.48, 95% CI: 0.26‐0.88, P = .018); however, patient (aHR: 0.93, 95% CI: 0.54‐1.59, P = .79) and graft survival (aHR: 0.89, 95% CI: 0.70‐1.13, P = .32) were similar between IRD and non‐IRD recipients. We recommend that IRDs be considered for transplant in children.     

The impact of direct‐acting antiviral agents on liver and kidney transplant costs and outcomes

Direct‐acting antiviral medications (DAAs) have revolutionized care for hepatitis C positive (HCV+) liver (LT) and kidney (KT) transplant recipients. Scientific Registry of Transplant Recipients registry data were integrated with national pharmaceutical claims (2007‐2016) to identify HCV treatments before January 2014 (pre‐DAA) and after (post‐DAA), stratified by donor (D) and recipient (R) serostatus and payer. Pre‐DAA, 18% of HCV+ LT recipients were treated within 3 years and without differences by donor serostatus or payer. Post‐DAA, only 6% of D‐/R+ recipients, 19.8% of D+/R+ recipients with public insurance, and 11.3% with private insurance were treated within 3 years (P < .0001). LT recipients treated for HCV pre‐DAA experienced higher rates of graft loss (adjusted hazard ratio [aHR] _1.341.85_2.10, P < .0001) and death (aHR _1.471.68_1.91, P < .0001). Post‐DAA, HCV treatment was not associated with death (aHR _0.340.67_1.32, P = .25) or graft failure (aHR _0.320.64_1.26, P = .20) in D+R+ LT recipients. Treatment increased in D+R+ KT recipients (5.5% pre‐DAA vs 12.9% post‐DAA), but did not differ by payer status. DAAs reduced the risk of death after D+/R+ KT by 57% (_0.190.43_0.95, P = .04) and graft loss by 46% (_0.270.54_1.07, P = .08). HCV treatment with DAAs appears to improve HCV+ LT and KT outcomes; however, access to these medications appears limited in both LT and KT recipients.     

Delayed graft function and acute rejection following HLA-incompatible living donor kidney transplantation

Incompatible living donor kidney transplant recipients (ILDKTr) have pre-existing donor-specific antibody (DSA) that, despite desensitization, may persist or reappear with resulting consequences, including delayed graft function (DGF) and acute rejection (AR). To quantify the risk of DGF and AR in ILDKT and downstream effects, we compared 1406 ILDKTr to 17 542 compatible LDKT recipients (CLDKTr) using a 25-center cohort with novel SRTR linkage. We characterized DSA strength as positive Luminex, negative flow crossmatch (PLNF); positive flow, negative cytotoxic crossmatch (PFNC); or positive cytotoxic crossmatch (PCC). DGF occurred in 3.1% of CLDKT, 3.5% of PLNF, 5.7% of PFNC, and 7.6% of PCC recipients, which translated to higher DGF for PCC recipients (aOR = _1.031.68_2.72). However, the impact of DGF on mortality and DCGF risk was no higher for ILDKT than CLDKT (p interaction > .1). AR developed in 8.4% of CLDKT, 18.2% of PLNF, 21.3% of PFNC, and 21.7% of PCC recipients, which translated to higher AR (aOR PLNF = _1.452.09_3.02; PFNC = _1.672.40_3.46; PCC = _1.482.24_3.37). Although the impact of AR on mortality was no higher for ILDKT than CLDKT (p interaction = .1), its impact on DCGF risk was less consequential for ILDKT (aHR = _1.341.62_1.95) than CLDKT (aHR = _1.962.29_2.67) (p interaction = .004). Providers should consider these risks during preoperative counseling, and strategies to mitigate them should be considered.     

Recipient Outcomes Following Transplantation of Allografts From Live Kidney Donors Who Subsequently Developed End‐Stage Renal Disease

Live kidney donors have an increased risk of end‐stage renal disease (ESRD) compared with nondonors; however, it is unknown whether undetected, subclinical kidney disease exists at donation that subsequently contributes to this risk. To indirectly test this hypothesis, the authors followed the donated kidneys, by comparing the outcomes of 257 recipients whose donors subsequently developed ESRD with a matched cohort whose donors remained ESRD free. The compared recipients were matched on donor (age, sex, race/ethnicity, donor–recipient relationship), transplant (HLA mismatch, peak panel‐reactive antibody, previous transplantation, year of transplantation), and recipient (age, sex, race/ethnicity, body mass index, cause of ESRD, and time on dialysis) risk factors. Median recipient follow‐up was 12.5 years (interquartile range 7.4–17.9, maximum 20 years). Recipients of allografts from donors who developed ESRD had increased death‐censored graft loss (74% versus 56% at 20 years; adjusted hazard ratio [aHR] 1.7; 95% confidence interval [CI] 1.5–2.0; p < 0.001) and mortality (61% versus 46% at 20 years; aHR 1.5; 95% CI 1.2–1.8; p < 0.001) compared with matched recipients of allografts from donors who did not develop ESRD. This association was similar among related, spousal, and unrelated nonspousal donors. These findings support a novel view of the mechanisms underlying donor ESRD: that of pre‐donation kidney disease. However, biopsy data may be required to confirm this hypothesis.     

Small donor size does not negatively impact outcomes after deceased-donor renal transplantation

Higher body mass index (BMI) of deceased-donors is associated with poorer outcomes in transplant recipients. The effect of low donor BMI on recipient graft function is not clear. Scientific Registry of Transplant Recipients data on recipients of deceased-donor kidneys from 2000 to 2019 were categorized by donor BMI (donor BMI < 18, 18-27, and >27). Primary outcome was death-censored graft survival. The impact of multiple recipient and donor variables, including low donor BMI and the difference between donor and recipient BMI, was evaluated using a multivariate Cox proportional-hazards model. Low BMI donors (LBD) were more likely to be younger, female, and white (all P < .05). LBD were less likely to be Hispanic, diabetic, or have hypertension (all P < .001). LBD recipients were more likely to be younger and female (both P < .001). Low donor BMI was not significantly associated with recipient graft survival. Donor-recipient BMI difference did not correlate with an increased risk of graft failure. Similar results were obtained when donors were classified using body surface area (BSA). Small donor size in terms of BMI or BSA or a large discrepancy between donor and recipient size should not necessarily preclude transplantation of an otherwise acceptable kidney.     

Pediatric deceased donor kidney transplant outcomes under the Kidney Allocation System

The Kidney Allocation System (KAS) has resulted in fewer pediatric kidneys being allocated to pediatric deceased donor kidney transplant (pDDKT) recipients. This had prompted concerns that post‐pDDKT outcomes may worsen. To study this, we used SRTR data to compare the outcomes of 953 pre‐KAS pDDKT (age <18 years) recipients (December 4, 2012–December 3, 2014) with the outcomes of 934 post‐KAS pDDKT recipients (December 4, 2014–December 3, 2016). We analyzed mortality and graft loss by using Cox regression, delayed graft function (DGF) by using logistic regression, and length of stay (LOS) by using negative binomial regression. Post‐KAS recipients had longer pretransplant dialysis times (median 1.26 vs 1.07 years, P = .02) and were more often cPRA 100% (2.0% vs 0.1%, P = .001). Post‐KAS recipients had less graft loss than pre‐KAS recipients (hazard ratio [HR]: _0.350.54_0.83, P = .005) but no statistically significant differences in mortality (HR: _0.290.72_1.83, P = .5), DGF (odds ratio: _0.931.32_1.93, P = .2), and LOS (LOS ratio: _0.961.06_1.19, P = .4). After adjusting for donor–recipient characteristics, there were no statistically significant post‐KAS differences in mortality (adjusted HR: _0.371.04_2.92, P = .9), DGF (adjusted odds ratio: _0.941.41_2.13, P = .1), or LOS (adjusted LOS ratio: _0.931.04_1.16, P = .5). However, post‐KAS pDDKT recipients still had less graft loss (adjusted HR: _0.380.59_0.91, P = .02). KAS has had a mixed effect on short‐term posttransplant outcomes for pDDKT recipients, although our results are limited by only 2 years of posttransplant follow‐up.     

Motivations and outcomes of compatible living donor–recipient pairs in paired exchange

Increasing numbers of compatible pairs are choosing to enter paired exchange programs, but motivations, outcomes, and system-level effects of participation are not well described. Using a linkage of the Scientific Registry of Transplant Recipients and National Kidney Registry, we compared outcomes of traditional (originally incompatible) recipients to originally compatible recipients using the Kaplan–Meier method. We identified 154 compatible pairs. Most pairs sought to improve HLA matching. Compared to the original donor, actual donors were younger (39 vs. 50 years, p < .001), less often female (52% vs. 68%, p < .01), higher BMI (27 vs. 25 kg/m², p = .03), less frequently blood type O (36% vs. 80%, p < .001), and had higher eGFR (99 vs. 94 ml/min/1.73 m², p = .02), with a better LKDPI (median 7 vs. 22, p < .001). We observed no differences in graft failure or mortality. Compatible pairs made 280 additional transplants possible, many in highly sensitized recipients with long wait times. Compatible pair recipients derived several benefits from paired exchange, including better donor quality. Living donor pairs should receive counseling regarding all options available, including kidney paired donation. As more compatible pairs choose to enter exchange programs, consideration should be given to optimizing compatible pair and hard-to-transplant recipient outcomes.     

Characterizing the landscape and impact of infections following kidney transplantation

Infections remain a major threat to successful kidney transplantation (KT). To characterize the landscape and impact of post-KT infections in the modern era, we used United States Renal Data System (USRDS) data linked to the Scientific Registry of Transplant Recipients (SRTR) to study 141 661 Medicare-primary kidney transplant recipients from January 1, 1999 to December 31, 2014. Infection diagnoses were ascertained by International Classification of Diseases, Ninth Revision (ICD-9) codes. The cumulative incidence of a post-KT infection was 36.9% at 3 months, 53.7% at 1 year, and 78.0% at 5 years. The most common infections were urinary tract infection (UTI; 46.8%) and pneumonia (28.2%). Five-year mortality for kidney transplant recipients who developed an infection was 24.9% vs 7.9% for those who did not, and 5-year death-censored graft failure (DCGF) was 20.6% vs 10.1% (P < .001). This translated to a 2.22-fold higher mortality risk (adjusted hazard ratio [aHR]: _2.152.22_2.29, P < .001) and 1.92-fold higher DCGF risk (aHR: _1.841.91_1.98, P < .001) for kidney transplant recipients who developed an infection, although the magnitude of this higher risk varied across infection types (for example, 3.11-fold higher mortality risk for sepsis vs 1.62-fold for a UTI). Post-KT infections are common and substantially impact mortality and DCGF, even in the modern era. Kidney transplant recipients at high risk for infections might benefit from enhanced surveillance or follow-up to mitigate these risks.     

Early steroid withdrawal in HIV-infected kidney transplant recipients: Utilization and outcomes

Kidney transplant (KT) outcomes for HIV-infected (HIV+) persons are excellent, yet acute rejection (AR) is common and optimal immunosuppressive regimens remain unclear. Early steroid withdrawal (ESW) is associated with AR in other populations, but its utilization and impact are unknown in HIV+ KT. Using SRTR, we identified 1225 HIV+ KT recipients between January 1, 2000, and December 31, 2017, without AR, graft failure, or mortality during KT admission, and compared those with ESW with those with steroid continuation (SC). We quantified associations between ESW and AR using multivariable logistic regression and interval-censored survival analysis, as well as with graft failure and mortality using Cox regression, adjusting for donor, recipient, and immunologic factors. ESW utilization was 20.4%, with more zero HLA mismatch (8% vs 4%), living donors (26% vs 20%), and lymphodepleting induction (64% vs 46%) compared to the SC group. ESW utilization varied widely across 129 centers, with less use at high- versus moderate-volume centers (6% vs 21%, P < .001). AR was more common with ESW by 1 year (18.4% vs 12.3%; aOR: _1.081.61_2.41, P = .04) and over the study period (aHR: _1.021.39_1.90, P = .03), without difference in death-censored graft failure (aHR _0.600.91_1.36, P = .33) or mortality (aHR: _0.751.15_1.77, P = .45). To reduce AR after HIV+ KT, tailoring of ESW utilization is reasonable.     

Turn down for what? Patient outcomes associated with declining increased infectious risk kidneys

Transplant candidates who accept a kidney labeled increased risk for disease transmission (IRD) accept a low risk of window period infection, yet those who decline must wait for another offer that might harbor other risks or never even come. To characterize survival benefit of accepting IRD kidneys, we used 2010‐2014 Scientific Registry of Transplant Recipients data to identify 104 998 adult transplant candidates who were offered IRD kidneys that were eventually accepted by someone; the median (interquartile range) Kidney Donor Profile Index (KDPI) of these kidneys was 30 (16‐49). We followed patients from the offer decision until death or end‐of‐study. After 5 years, only 31.0% of candidates who declined IRDs later received non‐IRD deceased donor kidney transplants; the median KDPI of these non‐IRD kidneys was 52, compared to 21 of the IRDs they had declined. After a brief risk period in the first 30 days following IRD acceptance (adjusted hazard ratio [aHR] accept vs decline: _1.222.06_3.49, P = .008) (absolute mortality 0.8% vs. 0.4%), those who accepted IRDs were at 33% lower risk of death 1‐6 months postdecision (aHR _0.500.67_0.90, P = .006), and at 48% lower risk of death beyond 6 months postdecision (aHR _0.460.52_0.58, P < .001). Accepting an IRD kidney was associated with substantial long‐term survival benefit; providers should consider this benefit when counseling patients on IRD offer acceptance.     

Comparing outcomes of third and fourth kidney transplantation in older and younger patients

Performing third or fourth kidney transplantation (3KT and 4KT) in older patients is rare due to surgical and immunologic challenges. We aimed to analyze and compare the outcomes of younger (18–64 years) and older (≥65 years) recipients of 3KT and 4KT. Between 1990 and 2016, we identified 5816 recipients of 3KTs (153 were older) and 886 recipients of 4KTs (18 were older). The incidences of delayed graft function (24.3% vs. 24.8%, p = .89), primary non-function (3.2% vs. 1.3%, p = .21), 1-year acute rejection (18.6% vs. 14.8%, p = .24), and 5-year death censored graft failure (DCGF) (24.8% vs. 17.9%, p = .06) were not different between younger and older recipients of 3KT. However, 5-year mortality was higher in older recipients (14.0% vs. 33.8%, p < .001) which remained significant after adjustment (aHR = 3.21, 95% CI: 2.59–3.99). Similar patterns were noted in the 4KT cohort. When compared with waitlisted patients, 3KT and 4KT are associated with a lower risk of mortality; aHR = 0.37, 95% CI: 0.33–0.41 and aHR = 0.31, 95% CI: 0.24–0.41, respectively. This survival benefit did not differ by recipient age (younger vs. older, p for interaction = 3KT: .49 and 4KT: .58). In the largest cohort described to date, we report that there is a survival benefit of 3KT and 4KT even among older patients. Although a highly selected cohort, our results support improving access to 3KT and 4KT.     

Inferior long‐term allograft and patient outcomes among recipients of offspring living donor kidneys

While offspring‐to‐parent living donor kidney transplantations may represent an ideal donor–recipient combination to optimize long‐term transplantation outcomes, the sex‐specific long‐term success of these transplantations remains unclear. We hypothesize that allograft and recipient survivals in offspring‐to‐parent living donor kidney transplantation differ between men and women due to donor‐specific alloimmunization during pregnancy. We retrospectively analyzed long‐term allograft and patient survival among men and women who received an offspring living donor kidney compared with those who received other haplotype‐matched living donor kidneys. Based on multivariable Cox proportional hazards modeling of Organ Procurement and Transplantation Network data from 2001 to 2015, we found that both men and women who received offspring living donor kidneys had significantly increased mortality compared with recipients who received nonoffspring living donor kidneys. While male recipients of any living donor kidney had greater risk of mortality and allograft failure than female recipients, there was no significant difference in all‐cause allograft failure or mortality in male versus female recipients of offspring living donor kidney transplantations. Our analysis demonstrated no significant interaction between recipient sex and donor offspring status. We conclude that nonoffspring living donors should be considered whenever feasible for both men and women with multiple donor options.     

Shipping living donor kidneys and transplant recipient outcomes

Kidney paired donation (KPD) is an important tool to facilitate living donor kidney transplantation (LDKT). Concerns remain over prolonged cold ischemia times (CIT) associated with shipping kidneys long distances through KPD. We examined the association between CIT and delayed graft function (DGF), allograft survival, and patient survival for 1267 shipped and 205 nonshipped/internal KPD LDKTs facilitated by the National Kidney Registry in the United States from 2008 to 2015, compared to 4800 unrelated, nonshipped, non‐KPD LDKTs. Shipped KPD recipients had a median CIT of 9.3 hours (range = 0.25‐23.9 hours), compared to 1.0 hour for internal KPD transplants and 0.93 hours for non‐KPD LDKTs. Each hour of CIT was associated with a 5% increased odds of DGF (adjusted odds ratio: 1.05, 95% confidence interval [CI], 1.02‐1.09, P < .01). However, there was not a significant association between CIT and all‐cause graft failure (adjusted hazard ratio [aHR]: 1.01, 95% CI: 0.98‐1.04, P = .4), death‐censored graft failure ( [aHR]: 1.02, 95% CI, 0.98‐1.06, P = .4), or mortality (aHR 1.00, 95% CI, 0.96‐1.04, P > .9). This study of KPD‐facilitated LDKTs found no evidence that long CIT is a concern for reduced graft or patient survival. Studies with longer follow‐up are needed to refine our understanding of the safety of shipping donor kidneys through KPD.