What is the purpose and interpretation of the Model for End-Stage Liver Disease (MELD) score?

Model for End-Stage Liver Disease (MELD) Score: Purpose and Interpretation

The MELD score is a validated scoring system designed to predict short-term (3-month) mortality in patients with end-stage liver disease, calculated using three objective laboratory parameters (serum bilirubin, serum creatinine, and INR), and is primarily used for liver transplant allocation to prioritize the sickest patients first. 1

MELD Score Calculation

The MELD score is calculated using the following formula:

MELD Score = 3.78 × log(bilirubin in mg/dL) + 11.2 × log(INR) + 9.6 × log(creatinine mg/dL) + 6.4 1

Key points about the calculation:

• Uses only objective laboratory parameters
• Logarithmic formula correlates directly with mortality risk
• Higher scores indicate increased mortality risk

Interpretation of MELD Scores

MELD scores correlate with the following mortality risks:

MELD Score	3-Month Mortality Risk
6-9	1.9%
10-19	6%
20-29	19.6%
30-39	52.6%
40+	71.3%

1

Clinical Applications

1. Liver Transplant Allocation

   • Primary use is prioritizing patients on liver transplant waiting lists
   • Benefits of transplantation typically emerge when MELD exceeds 14
   • MELD score ≥15 is the minimum recommended threshold for including patients on the transplant waiting list 1

2. Prognostic Tool in Various Clinical Scenarios

   • Variceal bleeding
   • Hepatorenal syndrome
   • Alcoholic hepatitis
   • Acute liver failure
   • Risk assessment for non-transplant surgery in cirrhotic patients
   • Risk assessment for TIPS procedures 1, 2

3. Monitoring Disease Progression

   • Regular monitoring recommended every 3-6 months in stable patients
   • More frequent monitoring (every 1-3 months) with clinical deterioration 1

Evolution of the MELD Score

The MELD score has undergone several refinements:

• Original MELD: Developed for TIPS patients in 1999 3
• MELDNa: Incorporated serum sodium to improve prediction accuracy 4
• MELD 3.0: Latest version that adds female sex and serum albumin as variables, with interactions between bilirubin and sodium and between albumin and creatinine 5

The MELD 3.0 has shown better discrimination than MELDNa (C-statistic, 0.869 vs 0.862) and addresses sex disparities in transplant allocation 5.

Advantages Over Other Scoring Systems

• More objective than Child-Turcotte-Pugh (CTP) score which includes subjective clinical parameters
• Superior for predicting short-term mortality
• More sensitive dynamic range than CTP
• Based entirely on laboratory values, reducing subjective assessment 1

Clinical Monitoring Recommendations

• Calculate MELD score every 6 months in stable patients
• Consider liver transplantation evaluation when:
  • MELD score ≥15
  • Major complications of cirrhosis occur (ascites, variceal bleeding, hepatic encephalopathy)
  • Patient reaches CTP class C 1

Limitations and Pitfalls

• Inaccurate in predicting survival in 15-20% of cases 3
• Very high MELD scores (>25) correlate with poorer post-transplant outcomes 1
• Female patients may have worse outcomes than males with the same MELD score 1, 5
• Does not account for some complications of portal hypertension (e.g., refractory ascites, hepatic encephalopathy)
• Laboratory variations can affect score calculation

The ongoing refinement of the MELD score (such as MELD 3.0) demonstrates the continued effort to improve its accuracy and address disparities in liver allocation.