Those of us involved in solid organ transplantation are faced with a question daily. That question is "when am I getting my liver?" The question is posed by patients, their family, or interested friends. In every case, I have to say, "I just don't know, it depends on your MELD score". And that's the truth. Most patients have at best a primitive understanding of the MELD score. The longer they are on the list for transplant, the better they grasp the concept and how the system works. Below I will give an overview of how the MELD system works, and what this means to the individual patient.
MELD stands for Model for End Stage Liver Disease, and was put into use in 2002. Before this time, patients needing liver transplants were grouped into four medical urgency categories. The categorieswere based on a scoring system that included some laboratory test results and some symptoms of liver disease. The symptoms of liver disease was difficult to control for and standardize. One concern with using symptoms in scoring was that different doctors might interpret the severity of those symptoms in different ways. In addition, this scoring system could not easily identify which patients had more severe liver disease and were in greater need of a transplant. Research showed that MELD accurately predict most liver patients’ short-term risk of death without a transplant. The MELD formulas are simple, objective and verifiable, and yield consistent results whenever the score is calculated.
Calculating the MELD score can easily be done from numerous web sites. Click here to calculate a MELD score. Scores can range from 6 (well) t0 40 (critical).
The factors that go into calculating the MELD score include bilirubin, INR, and serum creatinine. Additional points are given if the patient has been receiving dialysis withing the past week. There is discussion that other factors may eventually be used to calculate the score, but for now this is the best we have.
Bilirubin is elevated in chronic liver disease. Bilirubin is what gives the yellow skin color and jaundice seen in liver disease. The higher the bilirubin, the greater the jaundice. Bilirubin is an indirect marker of advanced liver disease. As a patient's liver status becomes worse, and thus more sick, the bilirubin will tend to rise. The higher the bilirubin, the higher MELD score. You can plug in different bilirubin values to see how this well effect the score. The normal bilirubin is generally less than 1 mg/dL.
The INR (International Normalized Ratio) is a lab test frequently used in liver disease. With advancing liver disease, the vitamin K dependant clotting factors, which happen to be manufactured in the liver, are reduced. This will result in a prolonged INR. A prolonged INR increases the MELD score.
Creatinine is a lab that measures kidney function. The kidney and liver are intimately related, in that as liver function declines, there is a high probability that kidney function will decline as well. Thus, an elevated creatine (worse kidney function) can be associated with advancing liver dysfunction and increased mortality and complication in the liver patient with advanced liver disease. Again, plug in different values for creatinine and you will see how the MELD will rise. A normal creatinine is usually less than 1 mg/dL.
Waiting time for transplant does not generally play much of a role in organ allocation. Patients listed for transplant earlier, when they may not need transplant, would be given an unfair advantage. Time on the list could be a factor if two identical MELD score patients were offered an organ.
The MELD score does not take into account various symptoms of chronic liver disease such as fatigue, depression, weakness, the presence of ascites, hepatic encephalopathy, or variceal bleeding. There are other symptoms that our patients report, not taken into strict accound in calculating the MELD score. Dealing with the symptoms, and the sense that they are getting more ill, is a very frustrating position for the patient, as well as the transplant team members. While we address and try to treat these symptoms, it is hard to accept their poor and declining quality of life does not come into consideration. Several medical conditions that had been considered in the prior liver allocation system, such as ascites and encephalopathy, are not included in the MELD system. This is because these factors have been tested in the MELD formula and did not add to the MELD score’s ability to predict death on the waiting list. In addition, the way these conditions are measured can vary from center to center; therefore, leaving them out of the MELD formula helps to make sure that all patients are scored the same way.
On exception is to appeal to the regional review committee, made up of transplant physicians in a similar region where the patient is listed. This is an opportunity for the team to "ask for more points" to increase the chances that someone will be transplanted.
How high your MELD score has to be before transplant varies on where you live. In the greater Houston area, a MELD of 22 and above (in general) will be a point where patients may be called for transplant. In California, a MELD score of over 30 will likely be needed for transplant.
So what is the bottom line on the MELD score? Time on the list is of little value, and that this model aims to transplant those that are sickest first. Despite multiple symptoms that patients report, and how bad they feel, it has not been shown that these symptoms lead to an increased chance of death. It is true that you have to get more sick before getting transplanted, but the survival afterwards, and the regaining of quality of life, is what makes the system work. It is far from perfect, but it does work.