Association of Kidney Donor Risk Index with the Outcome after Kidney Transplantation in the Eurotransplant Senior Program

The New UK National Kidney Allocation Scheme With Maximized "R4-D4" Kidney Transplants: Better Patient-to-Graft Longevity Matching May Be at the Cost of More Resources

OBJECTIVES

A new kidney matching scheme for allocation of deceased donor kidneys for transplantation was introduced in the United Kingdom in September 2019. Donors and recipients are stratified into quartiles derived from demographic and retrieval indices associated with risk of adverse outcome. We present data on 2 years of transplants, with the aim of understanding the potential impacts ofthe scheme on patient/transplant outcomes, hospitalization, and resource utilization.

MATERIALS AND METHODS

All deceased donortransplants from 2015 and 2016 were reclassified using the risk quartiles (D1-D4 for donor and R1-R4 for recipient, where 4 is highestrisk). Inpatientlength of stay, kidney function defined by estimated glomerular rate at 1 year, and patient survival data were collected.

RESULTS

Of the 195 deceased donor transplants analyzed, 144 recipients (73.4%) were in the highest risk R4 category, including 55 with R4-D4 combination (28.1%). Recipients in the R4 category had longer index admissions (mean of 12.4 vs 8.1 days for R1-R3; P = .002) and higher subsequent admission rates 90 days posttransplant(185.7 vs 122.7/1000 patient days for R1-R3; P < .001). Kidney transplant function at 1 year was lower for grafts categorized as D4 (mean estimated glomerular filtration rate of 35.7 vs 54.8 mL/min/1.73 m2 for D1-D3; P < .001). However, survival for R4 recipients with D4 kidneys was not significantly differentfrom R4 recipients with D1 to D3 kidneys (4-year patient survival rate with R4-D4 combination was 90.9%).

CONCLUSIONS

The principles ofthe allocation scheme in matching graft and patient survival were already largely being observed (matching higher risk deceased donor kidneys to higher risk recipients). However, an increase in D4 proportions in the R4 group may be associated with longer hospitalization posttransplant. Consideration should be given to mitigation strategies to address this. Despite poorer graft function, patient survival appears satisfactory.

Quality Assessment of Donor Kidneys and the Tendency of Kidney Acceptance: A Single-Center Experience

PURPOSE

The increasing age of donors and the increasing tendency of comorbidities requires an extension in acceptance criteria. In this review, the tendency for acceptance and refusal was analyzed by examining reasons for declining donor kidneys at the kidney transplantation center in Debrecen. This analysis aimed to assess the quality of donor kidneys and indicate why two-thirds of donated organs were refused.

METHOD

Our center in Debrecen received 535 kidney offers (based on exclusion criteria) between November 2016 and August 2019, which were retrospectively analyzed. Donor kidneys were evaluated using expanded criteria donor, kidney donor profile index (KDPI), and kidney donor risk index criteria systems.

RESULTS

Thirty-five percent (n = 189) of the kidneys offered to the center in Debrecen had been approved in advance, and later 63% (n = 119) were transplanted. Using the KDPI system, 41% of donors had a KDPI above 85, of which 23% were accepted, while acceptance of kidneys with a KDPI of 0 to 35 was around 70%. When examining causes of donor kidney refusal, 90% of the organs had donor quality problems, 13% had logistical cause (long cold ischemic time, large age difference between donor and recipient), and 10.5% had immunologic cause. In 13% of cases, the refusal of donor organs was due to the coexistence of several problems.

CONCLUSION

Our data showed that high-risk donor organs were being refused in our center; however, they are being transplanted at a higher rate in other Eurotransplant centers. The decision to refuse or accept donor organs depends on several factors, including expected waiting time, patient's clinical characteristics, and quality of life.

Should kidney allografts from old donors be allocated only to old recipients?

In several deceased donor kidney allocation systems, organs from elderly donors are allocated primarily to elderly recipients. The Eurotransplant Senior Program (ESP) was implemented in 1999, and since then, especially in Europe, the use of organs from elderly donors has steadily increased. The proportion of ≥60-year-old donors reported to the Collaborative Transplant Study (CTS) by European centers has doubled, from 21% in 2000-2001 to 42% in 2016-2017. Therefore, in the era of organ shortage it is a matter of debate whether kidney organs from elderly donors should only be allocated to elderly recipients or whether <65-year-old recipients can also benefit from these generally as "marginal" categorized organs. To discuss this issue, a European Consensus Meeting was organized by the CTS on April 12, 2018, in Heidelberg, in which 36 experts participated. Based on available evidence, it was unanimously concluded that kidney organs from 65- to 74-year-old donors can also be allocated to 55- to 64-year-old recipients, especially if these organs are from donors with no history of hypertension, no increased creatinine, no cerebrovascular death, and no other reasons for defining a marginal donor, such as diabetes or cancer.

A Retrospective Propensity Score Matched Analysis Reveals Superiority of Hypothermic Machine Perfusion over Static Cold Storage in Deceased Donor Kidney Transplantation

Hypothermic machine perfusion (HMP) has been introduced as an alternative to static cold storage (SCS) in kidney transplantation, but its true benefit in the clinical routine remains incompletely understood. The aim of this study was to assess the effect of HMP vs. SCS in kidney transplantation. All kidney transplants performed between 08/2015 and 12/2019 (n = 347) were propensity score (PS) matched for cold ischemia time (CIT), extended criteria donor (ECD), gender mismatch, cytomegalovirus (CMV) mismatch, re-transplantation and Eurotransplant (ET) senior program. A total of 103 HMP and 103 SCS instances fitted the matching criteria. Prior to PS matching, the CIT was longer in the HMP group (17.5 h vs. 13.3 h; p < 0.001), while the delayed graft function (DGF) rates were 29.8% and 32.3% in HMP and SCS, respectively. In the PS matched groups, the DGF rate was 64.1% in SCS vs. 31.1% following HMP: equivalent to a 51.5% reduction of the DGF rate (OR 0.485, 95% CI 0.318–0.740). DGF was associated with decreased 1- and 3-year graft survival (100% and 96.3% vs. 90.8% and 86.7%, p = 0.001 and p = 0.008) or a 4.1-fold increased risk of graft failure (HR = 4.108; 95% CI: 1.336–12.631; p = 0.014). HMP significantly reduces DGF in kidney transplantation. DGF remains a strong predictor of graft survival.

Outcomes of kidney transplantation from elderly deceased donors of a Korean registry

To overcome organ shortage, expanded criteria donors, including elderly deceased donors (DDs), should be considered. We analyzed outcomes of kidney transplantation (KT) from elderly DDs in a nationwide study. In total, data of 1049 KTs from DDs using the database of Korean Organ Transplantation Registry (KOTRY) were retrospectively analyzed based on the age of DDs: age ≥60 years vs. <60 years. Clinical information, graft status, and adverse events were reviewed in DDs and recipients. The mean age of the 1006 DDs was 51.04±10.54 years, and 21.5% of donors were aged ≥60 years. Elderly DDs had a significantly higher prevalence of diabetes and hypertension and higher Kidney Donor Risk Index (KDRI) and Kidney Donor Profile Index (KDPI). The mean age of the recipients was 47.45±14.87 years. Patients who received KT from elderly DDs were significantly older (53.12±15.14 vs. 45.88±14.41, P<0.001) and had a higher rate of diabetes (41.9 vs. 24.4%, P<0.001). Graft outcomes were not significantly different. Renal function was similar between the groups at the time of discharge and at 6 months, 1 year, and 2 years after KT. The rate of delayed graft function (DGF) was not significantly different. Risk factors of DGF were significantly different in DDs aged ≥60 years and <60 years. In the multivariable model, male sex (odds ratio: 3.99, 95% confidence interval: 1.42–11.22; P = 0.009) and KDRI (12.17, 2.23–66.34; P = 0.004) were significant risk factors for DGF in DDs aged ≥60 years. In DDs aged <60 years, thymoglobulin induction (2.62, 1.53–4.48; P<0.001) and continuous renal replacement therapy (3.47, 1.52–7.96; P = 0.003) were significant factors. Our data indicated that graft outcomes, including renal function and DGF, were similar for elderly DDs and DDs aged <60 years. Elderly DDs might be considered tolerable donors for KT, with active preoperative surveillance.

Transplanting Marginal Organs in the Era of Modern Machine Perfusion and Advanced Organ Monitoring

Organ transplantation is undergoing profound changes. Contraindications for donation have been revised in order to better meet the organ demand. The use of lower-quality organs and organs with greater preoperative damage, including those from donation after cardiac death (DCD), has become an established routine but increases the risk of graft malfunction. This risk is further aggravated by ischemia and reperfusion injury (IRI) in the process of transplantation. These circumstances demand a preservation technology that ameliorates IRI and allows for assessment of viability and function prior to transplantation. Oxygenated hypothermic and normothermic machine perfusion (MP) have emerged as valid novel modalities for advanced organ preservation and conditioning. Ex vivo prolonged lung preservation has resulted in successful transplantation of high-risk donor lungs. Normothermic MP of hearts and livers has displayed safe (heart) and superior (liver) preservation in randomized controlled trials (RCT). Normothermic kidney preservation for 24 h was recently established. Early clinical outcomes beyond the market entry trials indicate bioenergetics reconditioning, improved preservation of structures subject to IRI, and significant prolongation of the preservation time. The monitoring of perfusion parameters, the biochemical investigation of preservation fluids, and the assessment of tissue viability and bioenergetics function now offer a comprehensive assessment of organ quality and function ex situ. Gene and protein expression profiling, investigation of passenger leukocytes, and advanced imaging may further enhance the understanding of the condition of an organ during MP. In addition, MP offers a platform for organ reconditioning and regeneration and hence catalyzes the clinical realization of tissue engineering. Organ modification may include immunological modification and the generation of chimeric organs. While these ideas are not conceptually new, MP now offers a platform for clinical realization. Defatting of steatotic livers, modulation of inflammation during preservation in lungs, vasodilatation of livers, and hepatitis C elimination have been successfully demonstrated in experimental and clinical trials. Targeted treatment of lesions and surgical treatment or graft modification have been attempted. In this review, we address the current state of MP and advanced organ monitoring and speculate about logical future steps and how this evolution of a novel technology can result in a medial revolution.

Transplantation of Marginal Organs: Immunological Aspects and Therapeutic Perspectives in Kidney Transplantation

Recent data from the World Population Prospects projects that, by 2050, nearly all regions in the world will have a quarter or more of the population aged 60 and above. Chronic kidney disease (CKD) has a high global prevalence (~13%) worldwide, and the prevalence of chronic kidney disease and end-stage kidney disease increase with age. Kidney transplantation remains the best therapeutic option for end-stage kidney disease, offering a survival benefit in comparison with dialysis maintenance for most patients. This review focuses on immunological aspects of kidney transplantation in older patients and marginal donors, i.e., 60 years or older deceased kidney donors or 50–59 years old deceased kidney donors with comorbidities. Clinical outcomes of kidney recipients in terms of renal and patient survival are more than acceptable even for patients over 70. In this population, the first cause of graft loss is death with a functional graft. However, the inherent issues of these transplantations are the acceptance or refusal of frail kidney from an old donor and the increased immunogenicity of these organs in balance with potential frail and immunosenescent recipients. Finally, the immunosuppressive regimen itself is a challenge for the future of the transplant, to prevent adverse effects such as nephrotoxicity and higher risk of infections or cancer in a population already at risk. Belatacept may have a good place in the immunosuppressive strategy to improve efficacy and the safety posttransplantation.