Revisão Acesso aberto Revisado por pares

Changes in the United States Adult Heart Allocation Policy

2020; Lippincott Williams & Wilkins; Volume: 13; Issue: 10 Linguagem: Inglês

10.1161/circoutcomes.119.005795

ISSN

1941-7705

Autores

Supriya Shore, Jessica R. Golbus, Keith D. Aaronson, Brahmajee K. Nallamothu,

Tópico(s)

Heart Failure Treatment and Management

Resumo

HomeCirculation: Cardiovascular Quality and OutcomesVol. 13, No. 10Changes in the United States Adult Heart Allocation Policy Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessResearch ArticlePDF/EPUBChanges in the United States Adult Heart Allocation PolicyChallenges and Opportunities Supriya Shore, MD, MSCS Jessica R. Golbus, MD, MS Keith D. Aaronson, MD, MS Brahmajee K. NallamothuMD, MPH Supriya ShoreSupriya Shore Supriya Shore, MD, MSCS, University of Michigan, NCRC 16-169C, 2800 Plymouth Rd, SPC 2800, Ann Arbor MI 48109-2800. Email E-mail Address: [email protected] https://orcid.org/0000-0002-5436-6097 Department of Cardiovascular Disease, Division of Internal Medicine, University of Michigan, Ann Arbor. , Jessica R. GolbusJessica R. Golbus Department of Cardiovascular Disease, Division of Internal Medicine, University of Michigan, Ann Arbor. , Keith D. AaronsonKeith D. Aaronson Department of Cardiovascular Disease, Division of Internal Medicine, University of Michigan, Ann Arbor. , Brahmajee K. NallamothuBrahmajee K. Nallamothu Department of Cardiovascular Disease, Division of Internal Medicine, University of Michigan, Ann Arbor. Originally published29 Sep 2020https://doi.org/10.1161/CIRCOUTCOMES.119.005795Circulation: Cardiovascular Quality and Outcomes. 2020;13This article is commented on by the following:The New Adult Heart Allocation PolicyPOLICY STATEMENT TITLEOPTN/UNOS Policy Notice Proposal to Modify the Adult Heart Allocation SystemORGANIZATIONOPTN/UNOSRELEASE DATEImplemented October 18, 2018See Perspective by Colvin and RossPolicy ContextIn 1984, the National Organ Transplant Act was passed, which led to establishment of the Organ Procurement and Transplantation Network (OPTN) to ensure fair and equitable organ allocation (Figure). In 1986, OPTN contracted with the United Network for Organ Sharing (UNOS), a private nonprofit organization. Since its inception in 1988, the heart transplant (HT) allocation system of OPTN/UNOS has focused on listing patients based on severity of illness and time spent on a national waitlist. Initially, listing for HT was 2-tiered. With the introduction of left ventricular assist devices (LVADs), the allocation system was expanded to a 3-tiered system in 1998 (1A [high priority], 1B [intermediate priority], and 2 [low priority]) in an attempt to reduce waitlist time and mortality. In 2005, broader sharing rules were implemented to facilitate sharing over larger geographic areas, again in an attempt to reduce waitlist time for the most critically ill patients.1 With these changes, waitlist mortality initially declined.2 However, over the past decade, the HT waitlist has grown and at present lists over 4000 patients annually with ≈3000 HTs being performed nationally.3 By 2012, the number of patients listed as 1A and 1B had tripled, leading to a 3× higher waitlist mortality due to the longer waiting time for the most critically ill patients listed as 1A compared to those listed as 1B.4Download figureDownload PowerPointFigure. History of heart transplant allocation system. OPTN indicates Organ Procurement and Transplantation Network; and UNOS, United Network for Organ Sharing. *Details on allocation system provided in the Table.In light of these emerging data and concerns that the existing system was suboptimal, the OPTN/UNOS heart subcommittee initiated the process of refining the heart allocation criteria, leading to a newly revised allocation policy in December 2016 that was finally implemented in October 2018.5 In this policy brief, we review major deficiencies in the old allocation system, summarize new changes, and discuss their potential impact on the landscape of transplant medicine.Limitations of the Prior Allocation System and Changes in the New SystemThe biggest limitation of the old, 3-tiered system included inadequate risk estimation as patients listed as status 1A (high priority) comprised a heterogeneous group with differing waitlist mortalities.6 For example, a patient with a driveline infection, a relatively minor LVAD complication with a predicted waitlist mortality of 4.8%, would qualify for listing as status 1A, as would a patient on extracorporeal membrane oxygenation support with a nearly 10-fold higher predicted waitlist mortality of 35.7%.5 Moreover, the listing criteria did not require any objective physiological measurements to justify listing, leaving the system vulnerable to manipulation. This led to a large number of patients being listed as high priority for transplant and waitlist times prolonged to over 6 months.As a solution, the new allocation system has expanded the 3-tiered listing system to a 6-tiered system (Table) to better risk-stratify the heterogeneous group of patients previously listed as status 1A. This results in combining candidates with a similar waitlist and post-transplant mortality. The new system requires specific physiological criteria to meet some of the tier indications, such as the definition for cardiogenic shock (cardiac index <2.0 L/(kg·min) with a systolic blood pressure 15 mm Hg). For lower priority statuses, providers are now required to justify the need for treatment with high dose inotropes and to better classify complications related to LVAD therapy.Table Comparison of Adult Heart Allocation Criteria, 1988 to PresentAdult heart allocation1988-1998Adult heart allocation1999-2018Adult heart allocation2018 - presentStatus 1- Requiring any MCSD- Continuous intubation- Requiring ICU care with inotrope useStatus 1A- Admitted with TAH/ IABP/ ECMO- LVAD with complications- Continuous ventilation- Continuous single or multiple inotropes requiring hemodynamic monitoring- Dischargeable LVADs for 30 daysStatus 1- ECMO (up to 7 days)*- Non-dischargeable surgically implanted VAD- MCSD with life threatening ventricular arrhythmiaStatus 2- Intra-aortic balloon pump (up to 14 days)*- Sustained Ventricular tachycardia/ventricular fibrillation- Non-dischargeable, surgically implanted, non-endovascular LVAD (up to 14 days)*- MCSD with device malfunction/ mechanical failure- Total artificial heart- Dischargeable BiVAD or RVAD- Acute endovascular percutaneous circulatory support (up to 14 days)*Status 3- Dischargeable LVAD for up to 30 days- Multiple inotropes or single high dose inotropes with continuous hemodynamic monitoring- MCSD with device infection, hemolysis, pump thrombosis, right heart failure, mucosal bleeding, and aortic insufficiency- ECMO after 7 days or any other temporary MCSD after 14 daysStatus 1B- All LVADs- Continuous inotrope infusionStatus 4- Stable LVAD candidates not using 30-day discretionary period- Inotropes without hemodynamic monitoring- Congenital heart disease- Ischemic heart disease with intractable angina- Hypertrophic cardiomyopathy- Restrictive cardiomyopathy- Amyloidosis- Re-transplantStatus 5- Combined organ transplantsStatus 2- All other listed candidatesStatus 2- All other listed candidatesStatus 6- All other active candidatesBiVAD indicates biventricular assist device; ECMO, extracorporeal membrane oxygenation; IABP, intra-aortic balloon pump; ICU, intensive care unit; LVAD, left ventricular assist device; MCSD, mechanical circulatory support device; RVAD, right ventricular assist device; TAH, total artificial heart; and VAD, ventricular assist device.*At the completion of this specified time period, programs need to justify need for continued support.An additional issue with the 3-tiered listing system was inadequate sharing across geographic areas. Within this system, donation service areas (DSA) within a UNOS Region formed the starting point from where a donor heart became available for transplant. After the organ was offered to candidates listed as status 1A and 1B in the DSA itself, it would then be offered sequentially to other candidates across zones at increasing distances from the DSA. This favored less urgent candidates in the DSA over more urgent candidates not located in the DSA but who may have been located just a short distance outside the DSA boundary.5 Additionally, the DSA used zones based on fixed distance rings around donor hospitals. These simple zones ignored geography (eg, coastal areas have water bodies in their rings), resulting in supply-demand mismatch of donated organs across different regions and do not achieve fair organ distribution.7Accordingly, the new allocation system mandates organ sharing over a larger area and without regard to governmental boundaries. Status 1 and 2 candidates are now allowed to receive organs within a 500-mile radius irrespective of their DSA. Although this implies longer average graft ischemic time for the sickest candidates, the committee felt that the number of patients affected and the impact on post-transplant survival was likely to be small.Finally, the 3-tiered system did not serve patients with rarer causes of heart failure. These included patients with hypertrophic and restrictive cardiomyopathies and those with congenital heart disease, given their relative contraindication to LVADs and inotropes. The old allocation system required exception requests to justify their listing status (Table), further burdening the system. Reliance on exception requests required approval by a regional board and was thus subject to variability in acceptance rates by region.In comparison, the new allocation system now explicitly assigns a specific tier (status 4) for patients with congenital heart disease and those with restrictive and hypertrophic cardiomyopathies. Patients assigned to these tiers must meet prespecified criteria for illness severity, including hemodynamically significant heart failure or cardiac arrhythmias. However, upgrading these patients to an even higher priority still necessitates an exception request.DiscussionBy adding nuance to risk-stratification and broadening geographic organ sharing, the new allocation system is a step forward. Nonetheless, these changes also raise important questions: Will the added complexity provide clarity or additional burden? Will they optimize pretransplant and post-transplant morbidity and mortality and reduce wait times that have become excessive? Finally, will they begin to address a key underlying ethical challenge in transplant medicine where healthcare providers are left to advocate most strongly for their own individual patients, invariably placing value on one individual's life over that of another?Like the prior allocation scheme, the new criteria still continue to define highest urgency based, in part, on treatments administered rather than by disease severity. These may not always be aligned. Although the definition of cardiogenic shock is based on meeting set physiological criteria, evidence of end organ hypoperfusion, such as elevated lactate levels, is not required. Furthermore, patients in cardiogenic shock can be treated with inotropes or by using temporary mechanical circulatory support devices (MCSDs) or durable LVADs at the treating physician's discretion but with different implications for listing status. Because use of temporary MCSDs would result in a higher listing status, we anticipate greater utilization of temporary MCSDs including extracorporeal membrane oxygenation, analogous to the greater use of intravenous inotropes and pulmonary artery catheters following prior changes in donor heart allocation rules.8,9Such evidence is already accumulating. An early analysis from national UNOS data show that since implementation of the new allocation system, between October 2018 and March 2019, use of extracorporeal membrane oxygenation has increased 4-fold compared to the preceding 3 years. At the same time, a significant decrease in use of LVAD as a bridge to transplant strategy was observed.10 Furthermore, there is substantial variability across UNOS regions in the proportion of patients undergoing HT at these most urgent listing statuses, ranging from 29% in region 6% to 63% in region 8.11 This suggests providers may recommend placement of a balloon pump or extracorporeal membrane oxygenation to expedite transplantation, potentially exposing patients to higher daily risks of sepsis and stroke.12 Meanwhile, among patients with a durable LVAD listed for transplant, transplantation rates are low with a prolonged waitlist time, leading to greater a risk of LVAD related complication.10Another concern is that the updated allocation criteria increase the likelihood of transplantation for patients at the highest pretransplant risk yet many of these patients also have the highest post-transplant mortality. This underlying paradox in the allocation system is of particular concern due to broader organ sharing which also increases graft ischemic time.13 Recent report from UNOS showed that with the new allocation system 6-month survival was lower at 77.9% as compared to 93.4% in the older system.10Finally, the current allocation scheme does not provide exceptions for patients that are highly sensitized, leading to longer waitlist time and mortality. In addition, nearly 25% of US programs do not submit unacceptable antigen data to the OPTN database to maximize organ offers which in turn burden the system.14 At play is the inherent tension between individual and community ethics as physicians may choose to withhold antibody information to increase donation offers for sensitized patients.Application to Cardiovascular Disease CareQuality ImprovementThe new allocation policy aims to shorten time to HT for the sickest patients. However, it still does not provide long-lasting solutions to the waitlist crisis, perpetuating the supply-demand mismatch.12 This will require a larger donor pool, either through increased donation or increased utilization, or that the waitlist be shortened.3 Presumed consent, improved organ preservation, and donation after circulatory death could expand the donor pool, but the waitlist will continue to expand. With improving transplant outcomes over the past 30 years, eligibility for HT has widely expanded, and older patients with a greater number of comorbidities are being transplanted at higher rates. In 2018, 19.3% of transplant recipients were ≥65, whereas these patients constituted only 8.8% of all HTs in 1998. The trend towards transplanting more patients previously considered marginal is further magnified by allowing patients to shop across transplant centers for a favorable listing status. This favors affluent patients and promotes regional competition, violating the ethical mandate to equitable access. Although the new system is a step in the right direction, it remains to be seen how these issues will be impacted by the new policy.Next Steps and ResearchWe think 3 steps may help the transplant community as it begins to implement the new policy. First, we advocate for more research on increasing the donor pool. Nonetheless, even with use of marginal donors and donation after circulatory death, the demand for organ transplant will always outweigh the supply of donated organs. Continued improvements in durable LVADs, including introduction of fully implantable systems, are likely to play a larger role in the future. Second, the transplant community and its providers have an obligation to have better conversations with their patients about realistic alternatives to heart transplantation. This must include improved end of life discussions to ensure that resources are aligned not only with medical criteria but also with individuals' personal beliefs. Finally, although the new allocation system improves risk-stratification to identify the sickest patients needing HT, it is far from perfect. A better solution would be to create a heart allocation score, utilizing physiologically based predictions of pretransplant and post-transplant survival to better risk-stratify patients and ensure fairness in allocation. However, compared with other organs that have successfully used an allocation score for listing (eg, the Model for End-Stage Liver Disease score for liver disease), creation of a heart allocation score poses a vexing challenge. This is in part due to the variety of interventions that influence cardiac physiology—vasodilators, inotropes, and temporary MCSDs—the use of which can be driven both by reasonable differences in physician preference in the setting of uncertainty and by gaming. Moreover, as the field of MCSD is rapidly changing, using retrospective data to predict survival will be inaccurate. A heart allocation score would ideally incorporate predicted pre- and post-transplant mortality and allow for dynamic changes in listing status based on clinical events while enabling alignment between treatments administered and objective measures of disease severity.Sources of FundingDr Golbus is supported by grant T32-HL007853 from the National Institutes of Health.DisclosuresNone.FootnotesSupriya Shore, MD, MSCS, University of Michigan, NCRC 16-169C, 2800 Plymouth Rd, SPC 2800, Ann Arbor MI 48109-2800. Email [email protected]umich.eduReferences1. Colvin-Adams M, Valapour M, Hertz M, Heubner B, Paulson K, Dhungel V, Skeans MA, Edwards L, Ghimire V, Waller C, Cherikh WS, Kasiske BL, Snyder JJ, Israni AK. Lung and heart allocation in the United States.Am J Transplant. 2012; 12:3213–3234. doi: 10.1111/j.1600-6143.2012.04258.xCrossrefMedlineGoogle Scholar2. Singh TP, Almond CS, Taylor DO, Graham DA. Decline in heart transplant wait list mortality in the United States following broader regional sharing of donor hearts.Circ Heart Fail. 2012; 5:249–258. doi: 10.1161/CIRCHEARTFAILURE.111.964247LinkGoogle Scholar3. Stevenson LW. Crisis awaiting heart transplantation: sinking the lifeboat.JAMA Intern Med. 2015; 175:1406–1409. doi: 10.1001/jamainternmed.2015.2203CrossrefMedlineGoogle Scholar4. Colvin-Adams M, Smith JM, Heubner BM, Skeans MA, Edwards LB, Waller C, Snyder JJ, Israni AK, Kasiske BL. OPTN/SRTR 2011 Annual Data Report: heart.Am J Transplant. 2013; 13suppl 1119–148. doi: 10.1111/ajt.12023CrossrefMedlineGoogle Scholar5. Proposal to Modify the Adult Heart Allocation System, Organ Procurement and Transplantation Network. https://optn.transplant.hrsa.gov/media/2006/thoracic_brief_201612.pdf. Accessed February 25, 2019Google Scholar6. Dardas T, Mokadam NA, Pagani F, Aaronson K, Levy WC. Transplant registrants with implanted left ventricular assist devices have insufficient risk to justify elective organ procurement and transplantation network status 1A time.J Am Coll Cardiol. 2012; 60:36–43. doi: 10.1016/j.jacc.2012.02.031CrossrefMedlineGoogle Scholar7. Gentry SE, Massie AB, Cheek SW, Lentine KL, Chow EH, Wickliffe CE, Dzebashvili N, Salvalaggio PR, Schnitzler MA, Axelrod DA, Segev DL. Addressing geographic disparities in liver transplantation through redistricting.Am J Transplant. 2013; 13:2052–2058. doi: 10.1111/ajt.12301CrossrefMedlineGoogle Scholar8. Parker WF, Garrity ER, Fedson S, Churpek MM. Trends in the use of inotropes to list adult heart transplant candidates at status 1A.Circ Heart Fail. 2017; 10:e004483. doi: 10.1161/CIRCHEARTFAILURE.117.004483LinkGoogle Scholar9. Parker WF, Anderson AS, Hedeker D, Huang ES, Garrity ER, Siegler M, Churpek MM. Geographic variation in the treatment of U.S. adult heart transplant candidates.J Am Coll Cardiol. 2018; 71:1715–1725. doi: 10.1016/j.jacc.2018.02.030CrossrefMedlineGoogle Scholar10. Cogswell R, John R, Estep JD, Duval S, Tedford RJ, Pagani FD, Martin CM, Mehra MR. An early investigation of outcomes with the new 2018 donor heart allocation system in the United States.J Heart Lung Transplant. 2020; 39:1–4. doi: 10.1016/j.healun.2019.11.002CrossrefMedlineGoogle Scholar11. Organ Procurement and Transplantation Network. National Data.https://optn.transplant.hrsa.gov/data/view-data-reports/national-data/. Accessed February 27, 2019Google Scholar12. Teuteberg JJ, Stewart GC, Jessup M, Kormos RL, Sun B, Frazier OH, Naftel DC, Stevenson LW. Implant strategies change over time and impact outcomes: insights from the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support).JACC Heart Fail. 2013; 1:369–378. doi: 10.1016/j.jchf.2013.05.006CrossrefMedlineGoogle Scholar13. Meyer DM, Rogers JG, Edwards LB, Callahan ER, Webber SA, Johnson MR, Vega JD, Zucker MJ, Cleveland JC. The future direction of the adult heart allocation system in the United States.Am J Transplant. 2015; 15:44–54. doi: 10.1111/ajt.13030CrossrefMedlineGoogle Scholar14. Rogers JG. Changes in United States heart allocation: a community energized to improve policy.J Thorac Cardiovasc Surg. 2016; 152:1484–1486. doi: 10.1016/j.jtcvs.2016.07.077CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsRelated articlesThe New Adult Heart Allocation PolicyMonica M. Colvin, et al. Circulation: Cardiovascular Quality and Outcomes. 2020;13 October 2020Vol 13, Issue 10Article InformationMetrics Download: 213 © 2020 American Heart Association, Inc.https://doi.org/10.1161/CIRCOUTCOMES.119.005795PMID: 32988232 Originally publishedSeptember 29, 2020 Keywordsheart transplantationtransplantmortalityorganization, nonprofitpolicyPDF download SubjectsTransplantationEthics and Policy

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