What is the Model for End-Stage Liver Disease (MELD) score?

Model for End-Stage Liver Disease (MELD) Score

What the MELD Score Is

The MELD score is a validated, objective laboratory-based scoring system that predicts 3-month mortality in patients with end-stage liver disease using three parameters: serum bilirubin, international normalized ratio (INR), and serum creatinine. 1

The score was originally developed to assess short-term prognosis in patients undergoing transjugular intrahepatic portosystemic shunts (TIPS), but was subsequently adopted as the primary tool for prioritizing liver transplant allocation worldwide. 2, 1, 3

The Mathematical Formula

The MELD score calculation incorporates three objective laboratory values in a logarithmic formula: 1, 4

• 9.6 × log(creatinine mg/dL) - reflects renal function
• 3.8 × log(bilirubin mg/dL) - reflects hepatic synthetic function
• 11.2 × log(INR) - reflects coagulation status
• + 6.4 (constant)

The resulting score ranges from 6 to 40, with higher scores indicating greater disease severity and mortality risk. 1, 4

Primary Clinical Applications

Liver Transplant Allocation

MELD ≥15 is the established threshold for listing patients for liver transplantation, as patients with MELD ≤14 have better 1-year survival without transplantation than with it. 1, 5

The United Network for Organ Sharing uses MELD scores to prioritize allocation of deceased donor livers, transplanting the sickest patients first based on objective mortality risk rather than waiting time. 2, 1, 3

Mortality Prediction Across Multiple Clinical Scenarios

MELD accurately predicts short-term mortality in diverse contexts beyond transplant allocation: 1, 6

• Decompensated cirrhosis - general prognostication 6, 7
• Variceal bleeding - MELD score combined with hepatic encephalopathy predicts bleeding risk 6, 8
• Hepatorenal syndrome - incorporates renal dysfunction directly 6
• Alcoholic hepatitis - MELD >21 identifies high-risk patients, though cutoff values vary 2
• Perioperative risk assessment - for non-hepatic surgery or TIPS procedures 6
• Acute liver failure - short-term mortality prediction 6

Key Advantages Over Child-Pugh Score

MELD offers several critical advantages over the Child-Turcotte-Pugh classification: 1, 4

• Entirely objective laboratory-based criteria - eliminates subjective assessments of ascites and encephalopathy that plague Child-Pugh scoring 1, 4
• Continuous numerical scale - provides granular risk stratification from 6-40 rather than categorical classes 1, 4
• Includes renal function - serum creatinine captures hepatorenal syndrome and renal dysfunction, which Child-Pugh omits 1, 4

Important Limitations and Clinical Pitfalls

Creatinine Unreliability in Cirrhosis

Serum creatinine can be unreliable in cirrhotic patients, potentially overestimating renal dysfunction in patients with sarcopenia (low muscle mass) or underestimating it in those with fluid overload. 1

Patients on renal replacement therapy receive a maximum creatinine value of 4.0 mg/dL in the calculation, which may not fully capture their mortality risk. 1

Inter-Laboratory Variability

Despite mandatory round-robin testing, significant inter-laboratory differences exist in measuring bilirubin, INR, and creatinine, with discrepancies up to 5 MELD points between laboratories. 9 This creates potential inequities in transplant allocation based on which laboratory processes the samples.

Very High MELD Scores

MELD scores >30-35 are associated with increased post-transplant mortality and morbidity, requiring careful assessment of transplant candidacy. 1

Absolute contraindications at very high MELD include lactate >9 mmol/L, severe respiratory failure, and increasing vasopressor support. 1

Inaccuracy in 15-20% of Cases

MELD scores fail to predict mortality accurately in approximately 15-20% of patients with end-stage liver disease, highlighting the need for clinical judgment beyond the score alone. 6, 3

MELD Exception Points

Certain conditions warrant "exception points" because MELD inadequately reflects their mortality risk or transplant benefit: 1

• Hepatocellular carcinoma - standardized exception points required 1, 4
• Hepatopulmonary syndrome - severe hypoxemia not captured by MELD 1
• Portopulmonary hypertension - pulmonary vascular disease 1
• Refractory ascites - quality of life impairment 1

Do not use MELD as the sole criterion for transplant listing in patients with these conditions. 1

Enhanced MELD Variations

Several modifications have been proposed to improve predictive accuracy: 1, 4

• MELD-Na - incorporates serum sodium, improving prediction especially in patients with hyponatremia and ascites 1
• Delta MELD - measures change in MELD over time 1, 4
• MELD 3.0 - incorporates patient sex and albumin levels to reduce gender disparities 1

Clinical Management Algorithm Based on MELD Score

MELD ≥15: High-Risk Population Requiring Immediate Action

Patients with MELD ≥15 require immediate referral for liver transplantation evaluation. 1, 5

Specific actions include: 1

• Engage multidisciplinary transplant team immediately
• Identify and treat acute complications (variceal bleeding, hepatic encephalopathy, hepatorenal syndrome)
• Monitor MELD score regularly (weekly to monthly depending on stability)
• Consider living donor liver transplantation to reduce waitlist mortality 5

MELD <15: Lower-Risk Population

Focus on complication management and monitoring: 1

• Regular monitoring for disease progression (every 3-6 months)
• Treat specific cirrhosis complications as they arise
• Consider transplant evaluation if major complications occur despite optimal medical management
• Do not ignore clinical decompensation in patients with low MELD scores 1

Common Clinical Pitfalls to Avoid

Do not rely solely on MELD score when clinical decompensation is evident - refractory ascites, recurrent hepatic encephalopathy, and variceal bleeding indicate poor prognosis even with lower MELD scores. 1, 8

Do not delay transplant evaluation in patients with MELD ≥15 - waiting for further decompensation exposes patients to progressive complications that worsen post-transplant outcomes. 5

Do not overlook hepatocellular carcinoma screening - HCC requires exception points and may not be reflected in the MELD score. 1, 4