MELD / MELD-Na / MELD 3.0 (and PELD)

The Model for End-Stage Liver Disease (MELD) is a numeric score that estimates the short-term mortality risk of a patient with chronic liver disease and is used by the Organ Procurement and Transplantation Network (OPTN) to rank adult candidates for deceased-donor liver transplantation by medical urgency.[1][2] A higher MELD score corresponds to a higher risk of dying without a transplant and therefore higher priority on the liver match run.[1][2] The score has gone through three operational generations in U.S. allocation: the original MELD (sometimes called MELD 1.0), MELD-Na (which added serum sodium), and the current MELD 3.0, adopted in 2023.[2][3] A separate score, the Pediatric End-Stage Liver Disease (PELD) score, is used for candidates younger than 12.[2][4]

MELD is the engine of medical-urgency prioritization within OPTN allocation policy for the liver; the way the resulting priority interacts with geography is described in Geographic distribution and acuity circles. The score in allocation is capped and floored to a defined range, and certain candidates (for example, those with acute liver failure) may receive a higher-urgency status outside the MELD scale.[2][4]

Origin and adoption

MELD was originally developed around 2000 to predict survival after a transjugular intrahepatic portosystemic shunt (TIPS) procedure, using only objective laboratory values.[1][5] Because it relied on reproducible lab measurements rather than subjective clinical judgment, UNOS/OPTN adopted MELD on February 27, 2002 to replace the older Child-Turcotte-Pugh classification for prioritizing deceased-donor livers; the change shifted liver allocation from a system weighted toward waiting time and broad severity categories to one driven by an objective, continuously valued mortality estimate.[1][5] The original MELD used three laboratory variables: serum creatinine, total serum bilirubin, and the international normalized ratio (INR) of prothrombin time.[1][5]

In U.S. allocation, the MELD score is reported on an integer scale from 6 (less ill) to 40 (gravely ill), with the score capped at 40.[2][4]

MELD-Na (2016)

On January 11, 2016, OPTN implemented MELD-Na, which added serum sodium to the score.[3][5] The change was based on evidence that hyponatremia (low serum sodium) in advanced cirrhosis is associated with substantially increased waitlist mortality not captured by the original three variables, so incorporating sodium improved the score's prediction of who would die without a transplant and was projected to reduce waitlist deaths.[3][5] MELD-Na was the operational liver-urgency score from January 2016 until the adoption of MELD 3.0 in 2023.[3][5]

MELD 3.0 (2023)

OPTN adopted MELD 3.0 in 2023, replacing MELD-Na as the adult liver-allocation urgency score.[2][3] MELD 3.0 was developed to improve predictive accuracy and to reduce documented disparities, particularly a disadvantage faced by women under the older versions.[2][6] Relative to MELD-Na, MELD 3.0:[2][6]

• adds serum albumin as a variable;
• adds an adjustment of 1.33 points for female candidates, addressing evidence that earlier MELD versions under-estimated mortality risk in women (in part because serum creatinine tends to be lower in women for reasons unrelated to liver disease);
• introduces interaction terms (for example, between bilirubin and sodium, and between albumin and creatinine);
• updates the coefficients (weights) on the existing variables; and
• lowers the maximum (capped) creatinine value from 4.0 to 3.0 mg/dL (with values below 1.0 still set to 1.0).

So MELD 3.0 uses creatinine, bilirubin, INR, sodium, albumin, and a sex adjustment, on the same 6-to-40 allocation scale.[2][6] Monitoring after implementation reported that the share of newly registered liver candidates who were women rose, and that women became more likely to be added to the waitlist and to receive a transplant and less likely to die or be removed for being too sick, consistent with the policy's intent.[6]

PELD and PELD-Cr (pediatric)

For liver candidates younger than 12, OPTN uses the Pediatric End-Stage Liver Disease (PELD) score rather than MELD.[2][4] PELD is built around variables relevant to children with chronic liver disease, including bilirubin, INR, serum albumin, growth failure, and age at listing (younger than one year).[2][4] In conjunction with the MELD 3.0 update, OPTN updated the pediatric score so that creatinine is incorporated into the pediatric score (PELD-Cr), and transplant programs are required to submit creatinine values for pediatric candidates when adding or editing a candidate record.[2][4] As with adults, certain very high-risk pediatric candidates (for example, acute liver failure) qualify for a higher-urgency status outside the PELD scale.[2][4]

Use in allocation

MELD and PELD scores rank candidates by medical urgency within liver allocation, but they are not the only determinant of an offer.[2][4] A small number of candidates with very high short-term mortality are assigned the highest-urgency Status 1A (and pediatric Status 1B) categories, which take priority over MELD/PELD-ranked candidates.[2][4] In addition, certain conditions that the laboratory-based score does not adequately capture (for example, hepatocellular carcinoma within defined criteria, or other approved diagnoses) may receive standardized MELD/PELD exception points through a regional or national review process, granting a priority score different from the candidate's calculated laboratory score.[2][4] Finally, the priority that a MELD/PELD score confers is applied within the geographic framework then in force for the liver, which since 2020 has used fixed-distance acuity circles rather than the older donation service area and region.[2] The mechanical application of all of these factors is the match run.

See also

• OPTN allocation policy
• The match run
• Liver transplantation
• Geographic distribution and acuity circles
• Continuous distribution and the Composite Allocation Score
• The organ donation gap (national transplant waiting list)

References

• Current Status of Liver Allocation in the United States. Gastroenterol Hepatol (N Y). 2016. PMC4872844. https://pmc.ncbi.nlm.nih.gov/articles/PMC4872844/
• HRSA / OPTN. Improving Liver Allocation: MELD 3.0 FAQ. https://optn.transplant.hrsa.gov/media/fyxhlkp5/improving-liver-allocation-meld-30-faq.pdf
• HRSA / OPTN. Timeline of evolution of liver allocation and distribution policy. https://optn.transplant.hrsa.gov/policies-bylaws/a-closer-look/liver-timeline/
• HRSA / OPTN. Improving Liver Allocation: General Implementation FAQ. https://optn.transplant.hrsa.gov/media/ehtnanyg/improving-liver-allocation-general-implementation-faq.pdf
• UNOS / OPTN. Updates to medical urgency scoring for liver transplant candidates in effect (MELD 3.0). https://www.hrsa.gov/optn/news-events/news/updates-medical-urgency-scoring-liver-transplant-candidates-effect
• HRSA / OPTN. MELD 3.0 and PELD-Cr six-month monitoring report. https://www.hrsa.gov/sites/default/files/hrsa/optn/monitoringreport_liver_20240520_rptn.pdf