The waiting list for a transplant is determined by the severity of each patient's condition. There is currently no single prioritization system in Spain, so there are differences between centers when determining which patients have a more serious pathology and most urgently need a new organ.

To estimate this severity, a system developed in the United States called MELD was incorporated, a formula that combines the sum of several routine analytical parameters: serum creatinine, INR (related to blood clotting) and total serum bilirubin. Subsequently, the sodium value was incorporated, thus being called MELD-Na. The higher the score obtained in the formula, the more severe the patient is, allowing the waiting list to be ordered according to severity. Serum creatinine indicates the patient's renal function, which is directly related to mortality in patients with end-stage liver disease. However, creatinine is influenced by muscle mass, which is generally lower in women and in very malnourished patients. That is to say, “With identical renal function, women and also patients with malnutrition would show lower creatinine levels, obtaining a lower score and therefore lower priority for receiving a transplant”, explains Dr. Itxarone Bilbao, section head of the Hepatobiliary Surgery and Digestive Transplant Service at the Vall d’Hebron University Hospital and researcher in the Hepato-bilio-pancreatic Surgery (HBP) and Liver Transplant group at VHIR and the CIBER for Liver and Digestive Diseases (CIBEREHD).

In order to correct these differences, Vall d'Hebron has actively participated first in a national multicenter study and then in a consensus on prioritization of patients on the waiting list, promoted and financed by the Spanish Society of Liver Transplantation (SETH). Specialists in hepatology and surgery from all the State's liver transplantation units participated in this consensus, together with the National Transplant Organization (ONT) and donated as a result a document, published in the Revista Española de Enfermedades Digestivas.

Dr. Itxarone Bilbao explains that “among the recommendations of the Consensus there is the use of new prioritization models that correct the differences in products between men and women based on their muscle mass, weight and size”.

A new model to reduce the differences between homes and gifts

In a recent study, in which Vall d'Hebron will participate and the results of which will be published in the journal eClinicalMedicine of the Lancet portfolio, the MELD and MELD models will be compared with the new predictive models MELD 3.0 and the GEMA. Nah.

Ultimately, it is expected to end in collaboration with more than 20 hospitals in Spain and financed by the Carlos III Health Institute, including 6.071 patients on the waiting list for liver transplantation in some of the 25 hepatic transplant centers in Spain between 2016 and 2021.

The results of this study will show that approximately 10% of patients who need a liver transplant do not receive it because they are waiting for a suitable donor or because during the waiting period there is increased malaria so that they have of being excluded from the list. Això poses the need to implement the management model that prioritizes the most urgent patients.

The probability of mortality on the list or excluded by group in the first three months will be 5.4% in donations compared to 4.5% in homes, and these differences are imperceptible in daily clinical practice. Overall, after controlling for possible confounding factors, including the malady caused by transplantation and seriousness, the patients will present an increased risk of mortality in the list compared to both men. It can be seen that, indeed, children have lower creatinine levels than men and, therefore, a lower priority score on the list according to the MELD or MELD Na model.

“The study estimated that both MELD 3.0 and GEMA Na reduced this discrepancy, considering that the greatest implementation was obtained with the GEMA Na model. The application of GEMA could avoid one in every 18 deaths on the waiting list and, in the case of gifts, it would reduce one in every 15 deaths”, says Dr. Bilbao.

A consensus to optimize clinical practice

Currently, there is no single priority system for our country. Most centers manage the waiting list with their own criteria and only the autonomous communities, Andalusia and Catalonia, partially share the waiting list for older patients. To this heterogeneity that affects the gender disparity that exists in the access to transplantation and the expansion of indications in the future, especially in the oncological field, it is felt that there are clear guidelines for prioritization. With the idea of ​​establishing necessary recommendations, the Spanish Society of Liver Transplantation (SETH) has promoted a consensus ratified by all TH units and by the National Transplant Organization.

They establish that models that include serum sodium and those that include sex, such as MELD 3.0 and GEMA Na, are preferable because they better discriminate the probability of death and potentially eliminate gender disparity.

In Catalonia, a retrospective analysis is being carried out on the equity of the old MELD Na system in access to transplantation, in relation to variables such as sex, weight and height, with the idea of ​​adapting to changes in the dynamics of waiting list management in the fairest and most equitable way possible.