MELD—good for many, not as good for others … at least for now

Since its introduction in early 2002 as the prioritization system utilized by the United Network for Organ Sharing (UNOS) for patients on liver transplant waiting lists in the United States, the model for end stage liver disease (MELD) [1–3] has been extensively validated over time as a very sensitive predictor of pre-transplant mortality. Part of the success of the MELD system has been the foresight of UNOS to continuously reexamine MELD and be open to modifying it, so as to address inequities that might favor or prejudice certain patient groups. This is in fulfillment of the ‘‘final rule’’ of the organ procurement and transplantation network (OPTN) ensuring that all patients have as equal access to transplantation as possible [4]. For instance, in the early days of MELD, patients with small hepatocellular carcinoma (HCC) were given priority on the transplant waiting list (T1 lesions) and patients meeting the current T2 criteria were given higher priority than they currently have. T1 listing was done away with and patients with T2 criteria were assigned lower MELD scores when analysis suggested that patients with HCC were being given too much priority on the list and that non-HCC patients might be suffering the consequences of less access to organs and higher death rates on the waiting list [5, 6]. There are now specific disease states that allow patients to receive additional MELD priority scores, such as hepatopulmonary syndrome, portopulmonary hypertension, and familial amyloidosis [7]. Realization that patients with low MELD scores having hyponatremia are more likely to die on the waiting list has spurred ongoing research to assess whether an adjusted MELD score in this setting would be warranted [8]. Even patients having certain cholangiocarcinomas are now given priority in the waiting list because research has demonstrated appreciable survival with aggressive treatment protocols [9]. The success of MELD has captured the interest of the transplant community outside of the United States, and it has now been adopted by many other countries [10–13]. MELD has also been shown to have utility in predicting outcome in patients suffering from acute liver failure, alcoholic hepatitis, and in patients with chronic liver disease undergoing surgery or experiencing traumatic injury [14–18]. To date, however, it has not been shown to reliably predict post-liver transplant mortality. In listed patients with small changes in MELD score (delta MELD), there can be appreciable changes in pre-transplant mortality, although studies do not convincingly show this to be a strong predictor for having a bad outcome [19, 20]. In the issue of Hepatology International, Badr Al-Freah and colleagues [21] reviewed the results of an analysis of patients listed between 1998 and 2005 at the New Zealand Liver Transplant Unit with retrospective calculation of the MELD score at the time of listing and subsequently at the time of transplantation. They took into account prioritization points for HCC and studied 264 patients. Typically, patients in Australia and New Zealand are prioritized to transplantation when they are Child’s Class C and have had complications of portal hypertension, with hospitalized patients being further prioritized. The investigators found that MELD scores at transplant as well as delta MELD scores did not correlate with 3and 12-month post-transplant mortality. The authors concluded that the MELD allocation system would not be helpful in New Zealand, which has a single transplant center and organ procurement organization, and I am in agreement with this. Their results are not surprising in light of the fact that median waiting time prior to transplantation was 72 days and the MELD T. Schiano (&) Mount Sinai School of Medicine, New York, NY, USA e-mail: Thomas.Schiano@mountsinai.org