The Model for End-Stage Liver Disease (MELD) Scoring System
The MELD score is primarily designed to predict short-term (3-month) mortality in patients with end-stage liver disease and serves as the cornerstone for liver transplant allocation, prioritizing the sickest patients based on objective laboratory parameters rather than waiting time. 1
Components and Calculation
The MELD score is calculated using three objective laboratory parameters:
- Serum bilirubin (mg/dL)
- Serum creatinine (mg/dL)
- International Normalized Ratio (INR)
The formula is: MELD Score = 3.78 × log(bilirubin) + 11.2 × log(INR) + 9.6 × log(creatinine) + 6.4 1
Interpretation and Mortality Risk
The MELD score correlates directly with mortality risk, with higher scores indicating increased risk of death:
| MELD Score | 3-Month Mortality Risk |
|---|---|
| 6-9 | 1.9% |
| 10-19 | 6% |
| 20-29 | 19.6% |
| 30-39 | 52.6% |
| 40+ | 71.3% |
Clinical Applications
1. Liver Transplantation Allocation
- Primary use is prioritizing patients on the liver transplant waiting list
- Implemented in 2002, leading to reduced waiting list mortality without affecting post-transplant outcomes 3
- Minimum threshold of MELD ≥15 is recommended for listing patients for transplantation 1
- Benefits of transplantation typically emerge when MELD exceeds 14 1
2. Prognostic Tool in Various Clinical Scenarios
The MELD score effectively predicts outcomes in:
- Variceal bleeding
- Hepatorenal syndrome
- Alcoholic hepatitis
- Acute liver failure
- Risk assessment for non-transplant surgery in cirrhotic patients
- Risk assessment for TIPS (transjugular intrahepatic portosystemic shunt) procedures 4
Advantages Over Other Scoring Systems
- More objective than Child-Turcotte-Pugh (CTP) score, which includes subjective clinical parameters (encephalopathy and ascites)
- Superior for predicting short-term (3-month) mortality
- More sensitive dynamic range than CTP score
- Uses only laboratory values, eliminating subjectivity 1, 2
Limitations and Considerations
Fails to predict mortality in approximately 15% of patients with end-stage liver disease 4
Cannot accurately gauge severity in certain conditions:
- MELD exceptions (conditions where laboratory values don't reflect disease severity)
- Hepatocellular carcinoma in patients with compensated cirrhosis 5
Laboratory variability issues:
- Inter-laboratory differences can affect MELD calculation
- Variations of up to 5 MELD points have been documented between different laboratories 6
May not capture risk in specific populations:
- Female patients may have worse outcomes than males with the same MELD score 1
Monitoring Recommendations
- Calculate MELD score every 6 months in stable patients
- More frequent monitoring (every 1-3 months) in patients showing clinical deterioration
- Consider transplant evaluation when MELD score ≥15 or when major complications of cirrhosis occur 1
Potential Improvements
Several modifications have been proposed to enhance MELD's accuracy:
- Addition of serum sodium (MELD-Na)
- Incorporation of serum albumin
- Assessment of glucose intolerance
- Addition of APACHE II score
- Evaluation of MELD changes over time 4, 3
The MELD score represents a significant advancement in objectively assessing liver disease severity and has transformed liver allocation systems worldwide, though ongoing refinements continue to address its limitations.