Impact of Extending Eligibility for Reinstatement of Waiting Time After Early Allograft Failure: A Decision Analysis

RATIONALE & OBJECTIVE

The shortage of deceased donor kidneys identified for potential transplantation in the United States is exacerbated by a high proportion of deceased donor kidneys being discarded after procurement. We estimated the impact of a policy proposal aiming to increase organ utilization by extending eligibility for waiting time reinstatement for recipients experiencing early allograft failure after transplantation.

STUDY DESIGN

Decision analysis informed by clinical registry data.

SETTING & POPULATION

We used Organ Procurement and Transplantation Network data to identify 76,044 deceased-donor kidneys procured in the United States from 2013 to 2017, 80% of which were transplanted and 20% discarded.

INTERVENTION

Extend waiting time reinstatement for recipients experiencing allograft failure from the current 90 days to 1 year after transplantation.

OUTCOME

Net impact to the waitlist, defined as the estimated number of additional transplants minus estimated increase in waiting list reinstatements.

MODEL, PERSPECTIVE, & TIMEFRAME

We estimated (1) the number of additional deceased donor kidneys that would be transplanted if there was a 5%-25% relative reduction in discards, and (2) the number of recipients who would regain waiting time under a 6-, 12-, 18-, and 24-month reinstatement policy.

RESULTS

Reinstating a waiting time for recipients experiencing allograft failure up to 1 year after transplantation yielded more additional transplants than growth in additions to the waiting list for all model assumptions except the combination of a very low relative reduction in discards (5%) and a very high failure rate of transplanted kidneys that would previously have been discarded (≥5 times the rate of currently transplanted kidneys).

LIMITATIONS

Lack of empirical evidence supporting the proposed impact of such a policy change.

CONCLUSIONS

A policy change reinstating waiting time for deceased donor kidneys recipients with allograft failure up to 1 year after transplantation should explored as a decision science-based intervention to improve organ utilization.

Steatotic Livers Are More Susceptible to Ischemia Reperfusion Damage after Transplantation and Show Increased γδ T Cell Infiltration

Liver transplantation (LTx) is often the only possible therapy for many end-stage liver diseases, but successful long-term transplant outcomes are limited by multiple factors, including ischemia reperfusion injury (IRI). This situation is aggravated by a shortage of transplantable organs, thus encouraging the use of inferior quality organs. Here, we have investigated early hepatic IRI in a retrospective, exploratory, monocentric case-control study considering organ marginality. We analyzed standard LTx biopsies from 46 patients taken at the end of cold organ preparation and two hours after reperfusion, and we showed that early IRI was present after two hours in 63% of cases. Looking at our data in general, in accordance with Eurotransplant criteria, a marginal transplant was allocated at our institution in about 54% of cases. We found that patients with a marginal-organ LTx showing evidence of IRI had a significantly worse one-year survival rate (51% vs. 75%). As we saw in our study cohort, the marginality of these livers was almost entirely due to steatosis. In contrast, survival rates in patients receiving a non-marginal transplant were not influenced by the presence or absence of IRI. Poorer outcomes in marginal organs prompted us to examine pre- and post-reperfusion biopsies, and it was revealed that transplants with IRI demonstrated significantly greater T cell infiltration. Molecular analyses showed that higher mRNA expression levels of CXCL-1, CD3 and TCRγ locus genes were found in IRI livers. We therefore conclude that the marginality of an organ, namely steatosis, exacerbates early IRI by enhancing effector immune cell infiltration. Preemptive strategies targeting immune pathways could increase the safety of using marginal organs for LTx.

Assessment of Organ Quality in Kidney Transplantation by Molecular Analysis and Why It May Not Have Been Achieved, Yet

Donor organ shortage, growing waiting lists and substantial organ discard rates are key problems in transplantation. The critical importance of organ quality in determining long-term function is becoming increasingly clear. However, organ quality is difficult to predict. The lack of good measures of organ quality is a serious challenge in terms of acceptance and allocation of an organ. The underlying review summarizes currently available methods used to assess donor organ quality such as histopathology, clinical scores and machine perfusion characteristics with special focus on molecular analyses of kidney quality. The majority of studies testing molecular markers of organ quality focused on identifying organs at risk for delayed graft function, yet without prediction of long-term graft outcome. Recently, interest has emerged in looking for molecular markers associated with biological age to predict organ quality. However, molecular gene sets have not entered the clinical routine or impacted discard rates so far. The current review critically discusses the potential reasons why clinically applicable molecular quality assessment using early kidney biopsies might not have been achieved yet. Besides a critical analysis of the inherent limitations of surrogate markers used for organ quality, i.e., delayed graft function, the intrinsic methodological limitations of studies assessing organ quality will be discussed. These comprise the multitude of unpredictable hits as well as lack of markers of nephron mass, functional reserve and regenerative capacity.

Machine Perfusion of Extended Criteria Donor Organs: Immunological Aspects

Due to higher vulnerability and immunogenicity of extended criteria donor (ECD) organs used for organ transplantation (Tx), the discovery of new treatment strategies, involving tissue allorecognition pathways, is important. The implementation of machine perfusion (MP) led to improved estimation of the organ quality and introduced the possibility to achieve graft reconditioning prior to Tx. A significant number of experimental and clinical trials demonstrated increasing support for MP as a promising method of ECD organ preservation compared to classical static cold storage. MP reduced ischemia-reperfusion injury resulting in the protection from inadequate activation of innate immunity. However, there are no general agreements on MP protocols, and clinical application is limited. The objective of this comprehensive review is to summarize literature on immunological effects of MP of ECD organs based on experimental studies and clinical trials.

Transplantation of donor lungs with pulmonary embolism - a retrospective study

Lung transplantation from donors with fulminant pulmonary arterial embolism as a cause of death remains controversial. An analysis was performed comparing preoperative characteristics and outcomes of 25 donors with a primary diagnosis of pulmonary arterial embolism to 1085 recipients of donor lungs without pulmonary arterial embolism. No early functional impairment of donor lungs with pulmonary embolism was detectable as depicted by the incidence of primary graft dysfunction immediately after surgery (P = 0.66), 24 (P = 0.79), 48 (P = 0.99) and 72 h (P = 0.99) after transplantation. Pulmonary function testing at 1 year (P = 0.003) and at last outpatient control (P < 0.05) showed superior results in the cohort receiving lungs from donors with pulmonary embolism. Incidence of chronic lung allograft dysfunction (CLAD) showed no difference within the first year after lung transplantation, however, 5 year-CLAD free survival was superior in recipients (70.4% vs. 55.1%, P = 0.006) of donor lungs with pulmonary embolism. Overall survival was similar in both groups. Lungs from donors with fulminant pulmonary embolism prior to brain death can safely be used for lung transplantation without impairing postoperative outcomes. Lung function testing shows favorable midterm results in recipients of donor lungs with pulmonary embolism.