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Oversimplification and Misplaced Blame Will Not Solve the Complex Kidney Underutilization Problem

2022; Lippincott Williams & Wilkins; Volume: 3; Issue: 12 Linguagem: Inglês

10.34067/kid.0005402022

2641-7650

Darren Stewart, Bekir Tanrıöver, Gaurav Gupta,

Neurological and metabolic disorders

Introduction The Washington Post article "70 deaths, many wasted organs are blamed on transplant system errors" (1) and the Senate hearings of August 3, 2022 (2) both gave the misleading impression that the organ discard problem is primarily attributable to transportation-related mistakes, other human or system errors, and outdated computer technology that slows down the organ allocation process. As in all medical fields (3), transplantation is not immune to avoidable mishaps, which have indeed led directly to organs being rendered unusable (4). Additionally, the process of allocating less than ideal organs can indeed be painfully slow—so slow, in fact, that viable organs sometimes go unused due to the combined risk of elevated cold ischemia time (a common offer refusal reason) (5) and whatever factors led to the organ being deemed less than ideal in the first place (6,7). However, the predominant drivers of the nearly 25% kidney discard rate are not mishaps or poor technology. Rather, the US transplant system suffers from an organ offer refusal problem; far too many offers of imperfect but transplant-quality kidneys are refused on behalf of (or directly by) patients, prolonging the time it takes to find a clinically suitable "home" (patient) at a transplant center willing to take on the risk. In fact, the mean match run sequence number among accepted kidneys was recently estimated at 665, indicating that it is not atypical for hundreds—even thousands—of offers to be refused prior to finally securing an acceptance (8). After a kidney has a firm acceptance, the discard rate is only about 5% (8,9), indicating that approximately 80% of the discard problem is attributable to the inability to find an acceptor; a minority of discards occur postacceptance after an unexpected incident, such as a positive crossmatch, transportation delay, etc. The most common kidney discard reason reported by organ procurement organizations (OPOs) is, in fact, "no recipient located—list exhausted" (8,10,11), suggesting that OPOs attempted in vain to find an acceptor among all possible candidates. In an era of organ scarcity, where even the lowest-quality kidneys have been shown to confer a survival (and likely, quality of life) benefit over dialysis for many patients (12–14), how can it be that transplant decision making seems to reflect an era of plenty? Three Fundamental Realities Recent critics of the US transplant system seemingly fail to appreciate three fundamental realities of kidney transplantation relevant to the organ utilization challenge. (1) Not all donated kidneys are created alike. (2) The kidney allocation system is still largely tethered to the "first come, first served" fairness principle. (3) Major changes to organ allocation policy do not come easy. Critical comments about the US kidney discard rate seem to imply that the pool of available kidneys resembles a homogenous, fungible commodity, glossing over the fact that vast clinical differences exist among kidneys offered for transplant. Evaluating a deceased donor organ offer in many ways parallels shopping for a used car. A 20-year-old Civic with 175,000 miles on it might be perfectly adequate for "point A to B" travel for a few years, but clearly, it is not in the same league as a near-mint Lexus with under 10,000 miles coming off a short-term lease. Analogously, deceased donor kidneys vary substantially along a quality spectrum that portends highly differential expected graft longevity depending on donor age, medical history, etc. The decision to accept any particular kidney for any specific patient involves consideration of two key risks—graft failure and disease transmission (15)—along with tremendous uncertainty in how things will turn out for any given case (16,17), and it may very well be the most complex decision in all of medicine (18). A third critical dimension driving the complexity of the kidney acceptance decision is the very real possibility that another "better" kidney will soon be offered to the patient (19–21). If so, the right decision may indeed be to decline. Despite being substantially overhauled in 2014 (22), the "first come, first served" principle—a hallmark of fairness in the United States—is still largely entrenched into the kidney allocation system. Although arguably "fair," the by-product is that the transplant candidates who tend to be the first ones offered less than ideal kidneys are also among the first to receive offers for much higher-quality kidneys due to having accrued substantial qualified waiting (or dialysis) time. This aspect of the system induces a disincentive to accept imperfect kidneys for the candidates at the top of the match run. These early refusals slow down the placement process, leading to a cascade of further refusals as the cold ischemia clock keeps ticking (23), and the combination of the organ being "too old" and "too cold" requires a boldness that not even the most risk-tolerant transplant program is willing to take. Ways to Improve the System There is certainly room for improvement in the operational parameters and DonorNet system features that govern the mechanics of the organ offering process, most notably in the manner and timing in which offers are distributed and responded to (24). For example, the inefficient use of the "provisional yes" response has been a long-recognized pain point in the organ placement process (25). Encouragingly, the entire paradigm for sending and responding to offers is now being re-examined by the United Network for Organ Sharing (UNOS), with guidance from the Organ Procurement and Transplantation Network (OPTN) Operations & Safety Committee (26). Additionally, UNOS has recently implemented or begun piloting a number of sophisticated and potentially impactful DonorNet system enhancements: allowing users to see the complete donor record and respond to offers on a mobile device (27), allowing programs to avoid receiving unwanted offers by establishing multicriteria donor filters (28,29), and displaying novel predictive analytics (e.g., "time to next offer") to combat decision complexity (30). Still, the effect of operational and system features designed to foster faster progression down the match list has limited the potential to address the discard problem if the allocation system still results in first-offered candidates having a built-in disincentive to accept less than ideal kidneys. One of UNOS's stated aspirational goals is that no matter where on the quality spectrum an organ lies, the first person offered the organ should be the right one to accept it in terms of medical suitability, fairness, and the decision calculus surrounding the risks and benefits of accepting versus waiting for another. However, the current system built on a foundation emphasizing equity—not placement efficiency or maximizing organ utilization—is antithetical to that aspired reality. So how do we go from here—a system with built-in disincentives to accept offers—to there—a system that is still equitable but also "tuned for acceptance?" Kidney allocation policy should be modified in two key ways: by (1) changing the way waiting/dialysis time is used to prioritize patients and (2) codifying expedited placement pathways to aid OPOs in finding homes for hard to place kidneys. In some European countries' implementation of the Senior Program, in which older-donor kidneys are preferentially offered to older candidates, senior patients are required to choose one list—the older (age 65+) donor kidney list or the all other kidneys list—from which to receive offers; they cannot remain on both (31,32). The choice is clear—wait longer for a higher-quality organ or get transplanted more quickly with a shorter-longevity kidney. The Extended Criteria Donor and high Kidney Donor Profile Index (KDPI) programs were implemented in the United States such that candidates who choose to receive these offers also remain on the list for ideal-quality organs, weakening any incentive to accept the former given the very real possibility of receiving the latter. Reducing patients' options by segmenting the allocation system and forcing a choice between a shorter wait for a shorter longevity kidney and vice versa is not the only (or necessarily best) way to tune the decision-making calculus toward acceptance. Altering how waiting time is used to prioritize patients across the donor quality (e.g., KDPI) spectrum, according to a paradigm coined as "dealing from the bottom of the deck" (33,34), may be a more effective approach to consider as OPTN migrates to the continuous distribution framework (35,36). If a patient just added to the list with little or no waiting time priority for the best kidneys was given first dibs on a higher KDPI kidney, the incentive equation may change in a way that fosters securing offer acceptance earlier in the placement process (37). Given the drastic differences in kidney utilization practices among kidney programs (38), OPTN is implementing a new monitoring framework designed to exert upward pressure on and reduce variability in offer acceptance rates (39). Because the long-standing hyperfocus on early post-transplant success rates has contributed to risk aversion, "balancing the scorecard" in a way that calls out overly selective acceptance practices may help nudge the system toward transplanting more organs. However, because significant program to program variation is likely to persist, codifying into the kidney allocation policy a center-targeted expedited placement pathway may have even greater potential to reduce avoidable discards (40,41). Currently, to salvage an organ at high risk of discard, OPOs are permitted to deviate from the prescribed patient order and expedite placement to centers with a track record of accepting similar organs, bypassing higher-priority candidates at other centers. However, this practice is not standardized and varies widely, and thus, it is likely suboptimal in terms of utilization and may be inequitable in terms of organ distribution (42). Codifying an expedited placement system, as recommended by a National Kidney Foundation panel (43), into the kidney allocation system would include a predetermined, evidence-driven set of triggers that identify scenarios with an unusually high probability of discard under the standard (sequential) allocation approach (44). Determining the right parameters for an effective expedited placement allocation system may not be easy (45,46) but could have a significant effect if well engineered. Practical Challenges to Realizing Change Are such ideas—prioritizing just-listed patients ahead those with years on dialysis and bypassing more medically or ethically justified patients to expedite placement to patients at another center—fair, equitable, and legally permissible? Although these strategies would only be applied to a subset of donated organs, would such bold changes be perceived by patients and the broader transplant community as "unfair," potentially risking the foundation of trust that holds up the entire system? The OPTN Final Rule requires allocation policies to be equitable. However, a viable kidney that is discarded benefits no one. The transplant community may need to sacrifice some degree of geographic equity—where patients listed at the most aggressive programs will receive transplants faster than patients listed elsewhere—in order to have a meaningful effect on utility, recognizing that more transplants indirectly benefit all patients in need as a rising tide lifts all boats (47). The organ allocation policy development process in the United States is intentionally deliberative, involving numerous stakeholders, committee evidence gathering, formal public comment periods, and ultimately, Board of Directors' approval and implementation. OPTN aims to achieve broad consensus in developing and implementing new, often highly complex policies as expeditiously as possible, a colossal and underappreciated balancing act made all of the more challenging due to vested interests resistant to change (48). Achieving an acceptable balance between equity, utility, and efficiency has taken years (49,50)—a reality that should be recognized by critics who may assume the existence of an "easy button" for quickly improving such a complex system. Concluding Thoughts Individuals and institutions responsible for preventable errors should be held accountable to drive down the rate of mishaps. The logistics of organ transportation, for example, remain an area ripe for process improvement and technologic innovation (51–53). The OPTN Operations & Safety and Disease Advisory Committees should continue to embrace their mission and study transplant errors (4), disseminate process improvement successes to the community (54,55), and propose new policies as needed (56–58). Donor-derived disease transmissions attributable to the limitations of testing (i.e., "window period" infections) should be distinguished from avoidable transmissions caused by testing or communication errors (55,59). The risk of contracting a donor-derived infection should be recognized to be extremely low (approximately 0.18%) (60), far lower than the risks associated with remaining on dialysis (61,62). Also, OPOs should be held accountable to high standards through better metrics and tangible consequences of underperformance to ensure that significant opportunities for donation and transplantation are not being missed (63–65). Although the juxtaposition of "wasted organs" and "system errors" makes for a good headline, despite the system's flaws, the number of kidney transplants has increased 37% over the past 6 years from 18,597 in 2015 to a record 25,490 in 2021. The transplant community and its critics should recognize that the roots of the unacceptably high 20%–25% discard rate in the United States run deeper than the soundbites might suggest. Only after the true nature of the kidney discard problem (decision-making complexity) and the challenges in overcoming it (revising an allocation system still largely anchored in the deeply ingrained American ethic of "no cutting in line!") are fully appreciated will the transplant community be in a position to thoughtfully develop and enact truly impactful solutions. OPTN should not migrate kidney policy to the continuous distribution framework without incorporating bold policy changes that squarely address the kidney discard problem. Disclosures G. Gupta reports the consultancy agreements with CareDx; research funding from Merck Pharmaceuticals; honoraria from Alexion, CareDx, Mallinckrodt, Natera, and Veloxis; an advisory or leadership role with Frontiers of Medicine; an advisory or leadership role with the speakers bureaus of Alexion, CareDx, Mallinckrodt, and Veloxis; and other interests or relationships with the AST KPOP Executive Committee, the AST Transplant Nephrology Fellowship Accreditation Committee, and the National Kidney Foundation Virginia. D. Stewart reports the consultancy agreements with Hansa (consulting through UNOS Solutions) and Veloxis; research funding from Hansa Biopharma; and an advisory or leadership role as a Centers for Medicare & Medicaid Services (CMS)/Technical Assistance, Quality Improvement, and Learning (TAQIL)/ESRD Treatment Choice Learning Collaborative (ETCLC) National Faculty Member, as a CMS End-stage Renal Disease Treatment Choices Model Collaborative National Faculty Member, as an Scientific Registry of Transplant Recipients (SRTR) Review Committee Ex Officio Member, and with the SRTR Task 5 Steering Committee. All remaining authors have nothing to disclose. Funding None.