Variability in the reporting of renal function endpoints in immunosuppression trials in renal transplantation: time for consensus?

Benefits of Living Over Deceased Donor Kidney Transplantation in Elderly Recipients. A Propensity Score Matched Analysis of a Large European Registry Cohort

Although kidney transplantation from living donors (LD) offers better long-term results than from deceased donors (DD), elderly recipients are less likely to receive LD transplants than younger ones. We analyzed renal transplant outcomes from LD versus DD in elderly recipients with a propensity-matched score. This retrospective, observational study included the first single kidney transplants in recipients aged ≥65 years from two European registry cohorts (2013-2020, n = 4,257). Recipients of LD (n = 408), brain death donors (BDD, n = 3,072), and controlled cardiocirculatory death donors (cDCD, n = 777) were matched for donor and recipient age, sex, dialysis time and recipient diabetes. Major graft and patient outcomes were investigated. Unmatched analyses showed that LD recipients were more likely to be transplanted preemptively and had shorter dialysis times than any DD type. The propensity score matched Cox's regression analysis between LD and BDD (387-pairs) and LD and cDCD (259-pairs) revealing a higher hazard ratio for graft failure with BDD (2.19 [95% CI: 1.16-4.15], p = 0.016) and cDCD (3.38 [95% CI: 1.79-6.39], p < 0.001). One-year eGFR was higher in LD transplants than in BDD and cDCD recipients. In elderly recipients, LD transplantation offers superior graft survival and renal function compared to BDD or cDCD. This strategy should be further promoted to improve transplant outcomes.

Allograft Function as Endpoint for Clinical Trials in Kidney Transplantation

Clinical study endpoints that assess the efficacy of interventions in patients with chronic renal insufficiency can be adopted for use in kidney transplantation trials, given the pathophysiological similarities between both conditions. Kidney dysfunction is reflected in the glomerular filtration rate (GFR), and although a predefined (e.g., 50%) reduction in GFR was recommended as an endpoint by the European Medicines Agency (EMA) in 2016, many other endpoints are also included in clinical trials. End-stage renal disease is strongly associated with a change in estimated (e)GFR, and eGFR trajectories or slopes are increasingly used as endpoints in clinical intervention trials in chronic kidney disease (CKD). Similar approaches could be considered for clinical trials in kidney transplantation, although several factors should be taken into account. The present Consensus Report was developed from documentation produced by the European Society for Organ Transplantation (ESOT) as part of a Broad Scientific Advice request that ESOT submitted to the EMA in 2020. This paper provides a contemporary discussion of primary endpoints used in clinical trials involving CKD, including proteinuria and albuminuria, and evaluates the validity of these concepts as endpoints for clinical trials in kidney transplantation.

Do clinical trials reflect reality? A systematic review of inclusion/exclusion criteria in trials of renal transplant immunosuppression

Renal transplant recipients and donors are becoming increasingly more marginal, with more expanded criteria (ECD) and donation after circulatory death (DCD) donors and older recipients. Despite this, high-risk donors and recipients are often excluded from clinical trials, leading to uncertainty about the generalizability of findings. We extracted data regarding inclusion/exclusion criteria from 174 trials of immunosuppression in renal transplant recipients published over a 5-year period and compared criteria with those specified in published trial registries. Frequently reported donor exclusion criteria were age (16.1%), donor type and cold ischaemic time (22.4%). Common recipient exclusion criteria included upper age limit (38.5%), high panel reactive antibody (PRA) (42.5%) and previous transplantation (39.7%). Inclusion/exclusion criteria recorded in trial registries matched those reported in the manuscript in only 6 (7.8%) trials. Of registered trials, 51 (66.2%) trials included additional criteria in the manuscript, 51 (66.2%) were missing criteria in the manuscript specified in the protocol, and in 19 (24.7%) key criteria changed from the protocol to the manuscript. Our findings suggest many recent immunosuppression trials have restrictive inclusion criteria which may not be reflective of current renal transplant populations. Discrepancies between trial protocols and published reports raise the possibility of selection bias.

Toward Establishing Core Outcome Domains For Trials in Kidney Transplantation: Report of the Standardized Outcomes in Nephrology-Kidney Transplantation Consensus Workshops

BACKGROUND

Treatment decisions in kidney transplantation requires patients and clinicians to weigh the benefits and harms of a broad range of medical and surgical interventions, but the heterogeneity and lack of patient-relevant outcomes across trials in transplantation makes these trade-offs uncertain, thus, the need for a core outcome set that reflects stakeholder priorities.

METHODS

We convened 2 international Standardized Outcomes in Nephrology-Kidney Transplantation stakeholder consensus workshops in Boston (17 patients/caregivers; 52 health professionals) and Hong Kong (10 patients/caregivers; 45 health professionals). In facilitated breakout groups, participants discussed the development and implementation of core outcome domains for trials in kidney transplantation.

RESULTS

Seven themes were identified. Reinforcing the paramount importance of graft outcomes encompassed the prevailing dread of dialysis, distilling the meaning of graft function, and acknowledging the terrifying and ambiguous terminology of rejection. Reflecting critical trade-offs between graft health and medical comorbidities was fundamental. Contextualizing mortality explained discrepancies in the prioritization of death among stakeholders-inevitability of death (patients), preventing premature death (clinicians), and ensuring safety (regulators). Imperative to capture patient-reported outcomes was driven by making explicit patient priorities, fulfilling regulatory requirements, and addressing life participation. Specificity to transplant; feasibility and pragmatism (long-term impacts and responsiveness to interventions); and recognizing gradients of severity within outcome domains were raised as considerations.

CONCLUSIONS

Stakeholders support the inclusion of graft health, mortality, cardiovascular disease, infection, cancer, and patient-reported outcomes (ie, life participation) in a core outcomes set. Addressing ambiguous terminology and feasibility is needed in establishing these core outcome domains for trials in kidney transplantation.