MELD Score Threshold for Liver Transplantation
A MELD score of 15 is the established minimum threshold for listing patients for liver transplantation, as this represents the point where transplant benefit exceeds the risk of the procedure itself. 1, 2
The Evidence-Based Rationale for MELD ≥15
Patients with MELD scores below 15 have better 1-year survival WITHOUT transplantation than WITH it, making transplantation at lower scores potentially harmful rather than beneficial. 2, 3 This critical finding establishes MELD 15 as the point where transplant benefit begins to outweigh transplant risk.
The Italian consensus guidelines explicitly state that MELD 15 corresponds to a 5-year transplant benefit of 12 months of life gain, which represents the minimal acceptable benefit for listing. 1 This threshold balances:
- Urgency: The risk of waitlist mortality increases substantially above MELD 15 1
- Utility: Post-transplant outcomes remain favorable at this level 1
- Transplant benefit: The survival advantage with transplant versus without transplant becomes clinically meaningful 1, 3
How MELD Drives Organ Allocation
Once listed, the MELD score functions as a continuous prioritization system rather than a simple yes/no cutoff. 2 Higher MELD scores receive higher priority for organ allocation because they reflect greater short-term mortality risk (the score predicts 3-month mortality). 2, 4
The allocation system works as follows:
- MELD 15-24: Medium priority; moderate transplant benefit 5, 6
- MELD ≥25: High priority; substantial transplant benefit, though post-transplant outcomes begin to decline 5, 6, 7
- MELD >30-35: Very high mortality risk, but increased post-transplant complications require careful candidacy assessment 2
Critical Exceptions to the MELD System
Certain conditions receive "exception points" because MELD inadequately reflects their mortality risk or transplant benefit, including:
- Hepatocellular carcinoma (HCC): Tumor burden doesn't elevate MELD but significantly impacts prognosis 2, 4
- Hepatopulmonary syndrome: Severe hypoxemia with preserved liver function 2
- Portopulmonary hypertension: Pulmonary vascular disease complicating cirrhosis 2
- Refractory ascites or hepatic encephalopathy: Quality of life severely impaired despite potentially lower MELD 2, 8
These patients may be listed and prioritized despite MELD <15 through multidisciplinary team assessment. 1
Important Clinical Pitfalls
Do not rely solely on MELD score for transplant decisions in patients with HCC or other exception conditions, as the score will systematically underestimate their need for transplantation. 2, 4
Do not ignore clinical decompensation (variceal bleeding, encephalopathy, refractory ascites) in patients with MELD <15, as these complications may warrant listing despite the numerical threshold. 2, 8
Serum creatinine can be unreliable in cirrhotic patients, potentially overestimating renal dysfunction in sarcopenic patients or underestimating it in those with fluid overload, which may artificially inflate or deflate the MELD score. 2
Post-Transplant Outcomes by MELD Score
Higher pre-transplant MELD scores correlate with worse post-transplant survival, particularly in the first year. 5, 6, 7 However, this relationship is complex:
- MELD <15: Transplantation may cause net harm compared to natural disease course 3
- MELD 15-24: Optimal transplant benefit with acceptable post-transplant outcomes 5, 6
- MELD >25: Significant transplant benefit despite increased post-transplant mortality risk 5, 6, 9
Patients with MELD >25 at transplantation show greater improvement in quality of life measures post-transplant compared to those with lower MELD scores, suggesting that despite higher procedural risk, the functional benefit is substantial. 9
Disease-Specific Considerations
In hepatitis C patients, MELD scores >24 are associated with accelerated graft injury and lower survival, raising questions about optimal timing of transplantation in this population. 7
Cholestatic liver diseases show better post-transplant outcomes at equivalent MELD scores compared to hepatitis C or non-cholestatic diseases, suggesting that disease etiology modifies the MELD-outcome relationship. 5