Portal de Periódicos da CAPES

Model for end-stage liver disease exceptions: Proceed with caution

2011; Lippincott Williams & Wilkins; Volume: 17; Issue: 10 Linguagem: Inglês

10.1002/lt.22402

1527-6473

Kenneth Washburn,

Renal Transplantation Outcomes and Treatments

The Model for End-Stage Liver Disease (MELD) was implemented in the United States in 2002 with great success. At that time, hepatocellular carcinoma (HCC) patients meeting the T1 or T2 criteria were felt to be acceptable candidates; however, they needed additional or exception MELD points to supplement their often low native MELD scores in order to gain access to deceased donor liver allografts. In conjunction with the implementation of the MELD score, regional review boards were established for each United Network for Organ Sharing region in the United States. Through a peer review process, each regional review board would adjudicate petitions for increased MELD scores for patients in the region felt by their physicians to be not well represented by their calculated MELD scores. The increasing number of these petitions and the recognition that the MELD system did not always fairly represent some disease processes led to a consensus meeting in the United States in 2006.1 The results of that conference led to a number of recommendations for or against additional exception priority for specific disease entities. The subsequent adoption of some of these recommendations has resulted in a national exception priority policy for hepatopulmonary syndrome, familial amyloid polyneuropathy, cystic fibrosis, primary hyperoxaluria, portopulmonary hypertension, and cholangiocarcinoma. In addition to these conditions, some regions in the United States have agreements about awarding exception priority to patients with other disease entities, including HCC patients meeting expanded criteria. FLAS, French Liver Allocation Score; HCC, hepatocellular carcinoma; MELD, Model for End-Stage Liver Disease. The success of the MELD system in the United States has led other countries to adopt this system as the basis for liver allocation. In this issue of Liver Transplantation, Francoz et al.2 report on the French Liver Allocation Score (FLAS) and the ways in which exceptions are being handled. As the MELD system approaches its 10th year of use in the United States, almost everything is known about its abilities and drawbacks. Therefore, it is interesting and provocative to see how others with less experience are dealing with these peculiarities. One of the most obvious differences between the French and US systems is the approach to HCC. The FLAS does not consider HCC within the Milan criteria to be an exception. These patients are given additional priority on top of their native MELD scores until they undergo transplantation (preferably within 6 months). This approach is interesting because recent reports3, 4 and data suggest that in the United States, HCC patients are overly advantaged in the allocation system despite a number of policy changes that reduce exception scores for this group. The non-HCC exception diagnoses are at the heart of this report by Francoz et al.2 They list 16 different diagnostic conditions, and there are many similarities to the previous US report;1 however, with respect to the awarding of exception points, the conditions are not necessarily congruent. It is important to highlight a few differences. The FLAS exception system allows patients with ascites and encephalopathy to obtain additional priority, but this is not automatic. In the United States, these patients are generally not considered for additional priority at a national level or in most regions. In contrast, portopulmonary hypertension is given priority as a national policy in the United States but not in the FLAS system. Despite some differences, the FLAS and MELD exception systems overlap more than they diverge. What can we then infer from these similar allocation systems? Despite our best intentions, medicine remains as much an art as a science. As much as we may strive for consistency and homogeneity in the delivery of care and the approaches to diseases, practicing medicine is still an art, and not everything is prescriptive. However, when we are dealing with scarce and limited resources (eg, donated organs), there needs to be a fair, equitable, and transparent mechanism for the allocation of these precious assets. If a system is to be based on mortality (eg, dying on the waiting list for a liver transplant), invoking any other criteria such as the quality of life dilutes and distorts the system for all others. Allowing a subjective assessment (in some ways the art of medicine) to be combined with science (FLAS or MELD) results in a system that is neither equitable nor fair. Physicians want what is best for their patients. Allowing a subjective interpretation to play a role in the determination of disease severity when the stakes are high leads to a slippery slope. Before the implementation of the MELD score, the United States went through this scenario with the status 2a, 2b, and 3 criteria, which included ascites and encephalopathy as measures of disease severity. Evidence-based medicine must be used to substantiate additional priority for one patient group versus another, and the subjective elements must be removed or minimized to keep the system fair and transparent.5 An early analysis of regional review boards in the United States showed that this peer review process is quite good at distinguishing patients with a high risk of dying on the waiting list from those with a low risk.6 However, physicians who refer patients to regional review boards are unable to predict mortality well. We may conclude that physicians who are caring for these sick patients are able to objectively judge other patients with an increased mortality risk but perhaps not their own patients. A subsequent analysis of US patients who were granted nonstandard exceptions showed that these patients were granted significant priority: 39% of these patients underwent transplantation within 90 days, and this was similar to the situation for patients with MELD scores in the range of 21 to 30 who did not have an exception.7 Patients with non-HCC exceptions had wait-list death rates that were similar to those of patients with calculated MELD scores in the range of 11 to 20. This report also showed a gradual increase in the number and percentage of patients receiving non-HCC exceptions from 2003 to 2007. More recent data show that there has been a marked increase in the number of patients granted a nonstandard exception, with the vast majority for HCC not meeting the standard criteria (United Network for Organ Sharing, unpublished data, 2011). The FLAS system awards a score that presumably provides a patient access to liver transplantation within a set time period (often 3-6 months). This approach is not too dissimilar to the granting of MELD exceptions in the US system, which often awards increasing MELD scores every 3 months until transplantation, dropout, or death. I would challenge this mechanism and argue that if one thinks a patient warrants a transplant, give the patient the necessary risk score; however, without a change in the clinical scenario, there should be no systematic increases in the score. The policies in the United States and France do not give a stable patient with end-stage liver disease and a modest MELD score or FLAS an automatic score increase unless there is a change in the labs that reflects a change in the clinical condition. A strong argument can be made that these time-dependent increases in exceptions (HCC and non-HCC) are making the MELD score at transplant higher and higher in most regions in the United States. It will be interesting to see how this evolves with the FLAS and the exceptions put forward for that system. The challenge confronting these objective systems (FLAS and MELD) is to allow patients with diseases that have nonmortality endpoints (metastatic HCC) to exist with patients with diseases that have mortality endpoints. Evidence-based medicine must be used to combine these 2 groups, which are competing for the same limited resource. As a community, we have generally agreed that the MELD system is not perfect or exact, but it is a major step forward in allocation. It is incumbent upon the transplant community to keep the MELD and FLAS systems as objective as possible and not distorted by too many “exception” cases.