Personalizing Donor Kidney Selection: Choosing the Right Donor for the Right Recipient

Preoperative Risk Assessment of Early Kidney Graft Loss

Background

A large proportion of potential organ donors are not utilized for kidney transplantation out of risk of early allograft loss because of donor-related characteristics. These can be summarized using kidney donor profile index (KDPI). Because KDPI affects the choice of the recipient, the predictive ability of KDPI is tied to recipient attributes. These have been questioned to explain most of the predictive ability of KDPI. This study aims to quantify the effect of the donor on early graft loss (EGL) by accounting for nonrandom allocation.

Methods

This study included patients undergoing kidney transplantation from deceased donors between 2014 and 2020 from the Scientific Registry of Transplantation Recipients. EGL, defined as a return to dialysis or retransplantation during the first posttransplant year, was the primary endpoint. Nonrandom allocation and donor-recipient matching by KDPI necessitated the use of inverse probability treatment weighting, which served to assess the effect of KDPI and mitigate selection bias in a weighted Cox regression model.

Results

The study comprised 89 290 transplantations in 88 720 individual patients. Inverse probability treatment weighting resulted in a good balance of recipient covariates across values of continuous KDPI. Weighted analysis showed KDPI to be a significant predictor for short-term outcomes. A comparable (in terms of age, time on dialysis, previous transplants, gender, diabetes status, computed panel-reactive antibodies, and HLA mismatches) average recipient, receiving a kidney from a donor with KDPI 40-60 had a 3.5% risk of EGL increased to a risk of 7.5% if received a kidney from a KDPI >95 donor (hazard ratio, 2.3; 95% confidence interval, 1.9-2.7). However, for all-cause survival KDPI was less influential.

Conclusions

The predictive ability of KDPI does not stem from recipient confounding alone. In this large sample-sized study, modeling methods accounting for nonindependence of recipient selection verify graft quality to effectively predict short-term transplantation outcomes.

Quantifying the Effect of Consent for High-Kidney Donor Profile Index Deceased Donor Transplants in the United States

Key Points

Background

Despite known benefits of kidney transplantation, including transplantation from donors with increased risk factors, many waitlisted candidates die before transplantation. Consent to receive donor kidneys with lower expected survival (e.g., Kidney Donor Profile Index [KDPI] >85%) is typically obtained at waitlist placement. The presumed benefit of consent to receive high-KDPI donor kidneys is higher likelihood and timeliness of donor offers for transplantation. However, the specific effect of consent on access to transplantation is unclear. Our aims were to evaluate the characteristics of candidates consenting to high-KDPI donor kidneys and the likelihood of receiving a deceased donor transplant over time on the basis of consent.

Methods

We used national Scientific Registry of Transplant Recipients data between 2015 and 2022 (n=213,364). We evaluated the likelihood of consent using multivariable logistic models and time to deceased donor transplant with cumulative incidence plots accounting for competing risks and multivariable Cox models.

Results

Overall, high-KDPI consent was 41%, which was higher among candidates who were older, were Black or Hispanic, had higher body mass index, had diabetes, had vascular disease, and had 12–48 months prelisting dialysis time, with significant center-level variation. High-KDPI consent was associated with higher rates of deceased donor transplant (adjusted hazard ratio=1.15; 95% confidence interval, 1.13 to 1.17) with no difference in likelihood of deceased donor transplant from donors with KDPI <85%. The effect of high-KDPI consent on higher rates of deceased donor transplantation was higher among candidates older than 60 years and candidates with diabetes and variable on the basis of center characteristics.

Conclusions

There is significant variation of consent for high-KDPI donor kidneys and higher likelihood of transplantation associated with consent.

Deceased Donor Characteristics and Kidney Transplant Outcomes

Kidney transplantation is the therapy of choice for people living with kidney failure who are suitable for surgery. However, the disparity between supply versus demand for organs means many either die or are removed from the waiting-list before receiving a kidney allograft. Reducing unnecessary discard of deceased donor kidneys is important to maximize utilization of a scarce and valuable resource but requires nuanced decision-making. Accepting kidneys from deceased donors with heterogenous characteristics for waitlisted kidney transplant candidates, often in the context of time-pressured decision-making, requires an understanding of the association between donor characteristics and kidney transplant outcomes. Deceased donor clinical factors can impact patient and/or kidney allograft survival but risk-versus-benefit deliberation must be balanced against the morbidity and mortality associated with remaining on the waiting-list. In this article, the association between deceased kidney donor characteristics and post kidney transplant outcomes for the recipient are reviewed. While translating this evidence to individual kidney transplant candidates is a challenge, emerging strategies to improve this process will be discussed. Fundamentally, tools and guidelines to inform decision-making when considering deceased donor kidney offers will be valuable to both professionals and patients.

Influence of Donor Race and Donor-recipient Race-matching on Pediatric Kidney Transplant Outcomes

Existing literature has demonstrated the significant relationship between race and kidney transplant outcomes; however, there are conflicting and limited data on the influence of donor race or donor-recipient race-matching on pediatric kidney transplant outcomes.

Donor selection for multiorgan transplantation

PURPOSE OF REVIEW

There is limited data and guidance on donor selection for multiorgan transplantation. In this article, we review the current Organ Procurement and Transplantation Network policy on multiorgan allocation and the ideal donor criteria for each specific organ, in order to provide a framework to guide donor selection for various scenarios of multiorgan transplantation, including heart-kidney, heart-lung, heart-liver and heart-kidney-liver transplant procedures.

RECENT FINDINGS

Combined heart-kidney transplantation is the most common multiorgan transplant procedure and requires the most stringent HLA matching to ensure optimal graft survival. Using the virtual crossmatch and desensitization therapies can shorten waitlist times without increasing posttransplant rejection or mortality rates. The ideal heart-lung donor tends to be younger than other multiorgan transplants, and more tolerant to HLA mismatch, but ideally requires donors with no prior history of smoking, a short period of time on mechanical ventilation, adequate oxygenation and absence of pulmonary infection. The ideal heart-liver donor is often driven by criteria specific to the donor heart. Finally, several observational studies suggest that livers are more tolerant to HLA mismatch than other organs, and offer some degree of immune protection in combined organ transplants.

SUMMARY

Multiorgan transplantation is a steadily growing field. The required short ischemic time for the donor heart is often the limiting factor, as well as the scarcity of appropriate donors available within geographical confines. In general, as with single organ transplantation, younger age, size matching, few medical comorbidities and HLA compatibility confer the best posttransplant outcomes.

The Systemic Immune-Inflammation Index Predicts Clinical Outcomes in Kidney Transplant Recipients

BACKGROUND

Outcomes after kidney transplantation (KTx) remain limited by delayed graft function (DGF) and acute rejection. Non-invasive biomarkers may help identify patients at increased risk for these events. We examined the association between the systemic immune-inflammation index (SII), a novel inflammatory biomarker, and outcomes after KTx and evaluated its ability to predict post-transplant prognosis.

PATIENTS AND METHODS

Adult patients who underwent primary KTx at our institution between 2016-2019 were included. SII was calculated from pre-transplant complete blood counts as the ratio of the neutrophil count to the lymphocyte count multiplied by the platelet count. The cutoff between high and low SII was determined by maximizing the area under the curve. Multivariable logistic and Cox regression were used to identify factors associated with DGF and patient, rejection-free, and graft survival respectively.

RESULTS

Overall, 378 KTx recipients were included; 224 (59.3%) had high SII. On unadjusted analysis, high SII was associated with reduced odds of DGF, and improved patient and rejection-free survival. After adjustment, high SII was independently associated with improved patient survival alone. Multivariable models incorporating SII performed well for the prediction of DGF (c-statistic=0.755) and patient survival (c-statistic=0.786), though rejection-free survival was more difficult to predict (c-statistic=0.635).

CONCLUSION

SII demonstrated limited utility as an independent predictor of outcomes after KTx. However, in combination with other clinically relevant parameters, SII is a useful predictor of post-KTx prognosis. Validation of this novel inflammatory biomarker in a multi-institutional study is needed to further elucidate its practical applications in transplantation.

Outcomes in Living Donor Kidney Transplantation: The Role of Donor's Kidney Function

INTRODUCTION

Living donor kidney transplant (LDKT) is one of the best therapeutic options for end-stage kidney disease (ESKD). Guidelines identify different estimated glomerular filtration rate (eGFR) thresholds to determine the eligibility of donors. The aim of our study was to evaluate whether pretransplant donor eGFR was associated with kidney function in the recipient.

METHODS

We retrospectively studied LDKT recipients who received a kidney graft between September 1, 2005, and June 30, 2016 in the same transplant center in France and that had eGFR data available at 3, 12, 24, and 36 months posttransplant.

RESULTS

We studied 90 donor-recipient pairs. The average age at time of transplant was 51.47 ± 10.95 for donors and 43.04 ± 13.52 years for recipients. Donors' average eGFR was 91.99 ± 15.37 mL/min/1.73 m2. Donor's age and eGFR were significantly correlated (p < 0.0001, r2 0.023). Donor's age and eGFR significantly correlated with recipient's eGFR at 3, 12, and 24 months posttransplant (age: p < 0.001 at all intervals; eGFR p = 0.001, 0.003, and 0.016, respectively); at 36 months, only donor's age significantly correlated with recipient's eGFR. BMI, gender match, and year of kidney transplant did not correlate with graft function. In the multivariable analyses, donor's eGFR and donor's age were found to be associated with graft function; correlation with eGFR was lost at 36 months; and donor's age retained a strong correlation with graft function at all intervals (p < 0.001).

CONCLUSIONS

Donor's eGFR and age are strong predictors of recipient's kidney function at 3 years. We suggest that donor's eGFR should be clinically balanced with other determinants of kidney function and in particular with age.

Degree of Glomerulosclerosis in Procurement Kidney Biopsies from Marginal Donor Kidneys and Their Implications in Predicting Graft Outcomes

Background: This study aimed to assess the association between the percentage of glomerulosclerosis (GS) in procurement allograft biopsies from high-risk deceased donor and graft outcomes in kidney transplant recipients. Methods: The UNOS database was used to identify deceased-donor kidneys with a kidney donor profile index (KDPI) score > 85% from 2005 to 2014. Deceased donor kidneys were categorized based on the percentage of GS: 0-10%, 11-20%, >20% and no biopsy performed. The outcome included death-censored graft survival, patient survival, rate of delayed graft function, and 1-year acute rejection. Results: Of 22,006 kidneys, 91.2% were biopsied showing 0-10% GS (58.0%), 11-20% GS (13.5%), >20% GS (19.7%); 8.8% were not biopsied. The rate of kidney discard was 48.5%; 33.6% in 0-10% GS, 68.9% in 11-20% GS, and 77.4% in >20% GS. 49.8% of kidneys were discarded in those that were not biopsied. Death-censored graft survival at 5 years was 75.8% for 0-10% GS, 70.9% for >10% GS, and 74.8% for the no biopsy group. Among kidneys with >10% GS, there was no significant difference in death-censored graft survival between 11-20% GS and >20% GS. Recipients with >10% GS had an increased risk of graft failure (HR = 1.27, p < 0.001), compared with 0-10% GS. There was no significant difference in patient survival, acute rejection at 1-year, and delayed graft function between 0% and 10% GS and >10% GS. Conclusion: In >85% KDPI kidneys, our study suggested that discard rates increased with higher percentages of GS, and GS >10% is an independent prognostic factor for graft failure. Due to organ shortage, future studies are needed to identify strategies to use these marginal kidneys safely and improve outcomes.