MELD和PELD评分标准及其计算方法

liver411

The United Network for Organ Sharing (UNOS), a non-profit charitable
organization, operates the Organ Procurement and Transplantation Network
(OPTN) under federal contract. On an ongoing basis, the OPTN/UNOS
evaluates new advances and research and adapts these into new policies to
best serve patients waiting for transplants.
As part of this process, the OPTN/UNOS developed a system for prioritizing
candidates waiting for liver transplants based on statistical formulas that are
very accurate for predicting who needs a liver transplant most urgently.
The MELD (Model for End Stage Liver Disease) is used for candidates age 12
and older and the PELD (Pediatric End Stage Liver Disease Model) is used
for patients age 11 and younger.
This document will explain the system and how it affects those needing a transplant.

What is MELD? How will it be used?The Model for End-Stage Liver Disease (MELD) is a numerical scale, ranging
from 6 (less ill) to 40 (gravely ill), used for liver transplant candidates age 12
and older. It gives each person a ‘score’ (number) based on how urgently he
or she needs a liver transplant within the next three months. The number is
calculated by a formula using three routine lab test results:
I bilirubin, which measures how effectively the liver excretes bile;
I INR (prothrombin time), which measures the liver’s ability to make blood
clotting factors; and
I creatinine, which measures kidney function. (Impaired kidney function is
often associated with severe liver disease.)
The only priority exception to MELD is a category known as Status 1. Status 1 patients
have acute (sudden and severe onset) liver failure and a life expectancy of
hours to a few days without a transplant. Less than one percent of liver
transplant candidates are in this category. All other liver candidates age 12
and older are prioritized by the MELD system.
A patient’s score may go up or down over time depending on the status of his
or her liver disease. Most candidates will have their MELD score assessed a
number of times while they are on the waiting list. This will help ensure that
donated livers go to the patients in greatest need at that moment.
美国器官移植共享网－一个非营利的慈善组织，在联邦体制下运行器官切取和移植方面的网络。在不断前进的基础之上，OPTN/UNOS对新的进展和研究进行了评价，使之适应新的政策，以便更好的为等待移植患者服务。作为此项计划的一部分，OPTN/UNOS提出了一种新系统，以便更好的对等待肝移植患者进行划分等级，该系统是建立在统计公式基础之上，可以非常精确的估计哪个患者更迫切需要肝移植。MELD（终末期肝病模型）用于年龄>=12岁的患者， PELD （小儿终末期肝病模型）用于年龄<=11岁患者。

什么是MELD？怎样使用MELD？
MELD是一个从6（轻微疾病）到40（严重疾病）变化的数字范围，用于年龄>=12岁的等待移植的患者，其在他或她在三个月内需要肝移植的迫切程度的基础上，给了每个人一个分数（数字）。这个数字是根据三个常规的实验室检查结果通过一个公式计算出来的：
胆红素：检查肝脏分泌胆汁的功能
国际标准化比率（凝血酶原时间）：检查肝脏生成凝血因子的能力
肌酐：检查肾脏功能（与严重肝脏疾病相关的肾功能损害）
MELD唯一例外优先的是这种情况：这种该患者有急性肝衰（突发或起病严重），如果没有移植的话，其与其寿命只有几个小时到几天。仅仅有不到1%的患者属于这种情况。所有其他年龄>=12岁的患者是按照MELD系统进行评估的。
一个患者的分数可能会根据其肝脏疾病的状况升高或者降低。大部分等待肝移植患者，会对其进行多次MELD评分。这样可以确保供肝能够给与那些最需要的患者。
What is PELD? How does it differ from MELD?
Candidates age 11 and younger are placed in categories according to the
Pediatric End-stage Liver Disease (PELD) scoring system. Again there is a Status 1
category for highly urgent patients, representing about one percent of those
listed. All other candidates in this age range receive priority through PELD.
PELD is similar to MELD but uses some different factors to recognize the specific
growth and development needs of children. PELD scores may also range higher
or lower than the range of MELD scores. The measures used are as follows:
I bilirubin, which measures how effectively the liver excretes bile;
I INR (prothrombin time), which measures the liver’s ability to make blood
clotting factors;
I albumin, which measures the liver’s ability to maintain nutrition;
I growth failure; and
I whether the child is less than one year old.
As with MELD, a patient’s score may go up or down over time depending on
the status of his or her disease. Most candidates will have their PELD score
assessed a number of times while they are on the waiting list. This will help
ensure that donated livers go to the patients in greatest need at that moment.

PELD是什么？其和MELD的区别在哪里？
年龄<=11岁患者根据PELD评分系统划分为一类。同样，也有一种高危患者属于例外，在等待移植患者中仅占不到1%.所有该年龄段的其他患者都可以通过PELD进行划分。PELD与MELD相似，但是考虑到儿童生长发育的需要，使用一些不同的因子。PELD与MELD评分一样，也可能升高或下降。使用指标如下：
胆红素：检查肝脏分泌胆汁的功能
国际标准化比率（凝血酶原时间）：检查肝脏生成凝血因子的能力生长不足
该小儿是否小于1岁。与MELD一样，一个患者的分数可能会根据其肝脏疾病的状况升高或者降低。大部分等待肝移植患者，会对其进行多次PELD评分。这样可以确保供肝能够给与那些最需要的患者。

What Led To the MELD/PELD System?
Until 2002, patients needing liver transplants were grouped into four medical
urgency categories. The categories were based on a scoring system that
included some laboratory test results and some symptoms of liver disease.
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 and PELD accurately predict most liver patients’
short-term risk of death without a transplant. The MELD and PELD formulas
are simple, objective and verifiable, and yield consistent results whenever the
score is calculated.

OPTN/UNOS committees developed the liver policy based on MELD and
PELD, with key support from transplant patient/family advocates. It was
approved by the OPTN/UNOS Board of Directors in November 2001 and went
into effect in February 2002.

PELD与MELD评分系统是怎样产生的？
2002年之前，需要肝移植的患者被分为四种紧急类别。这种分类是根据包括一些实验室检查结果和一些肝病症状的一种评分系统进行。一个担忧就是利用症状进行评分，不同的医生可能会会对症状的严重性有不同的认识。此外，这种评分系统不容易鉴别哪些患者有更为严重的肝病，更加需要肝移植。研究显示，MELD 与 PELD能精确的预测大部分肝病患者不行肝移植的短期死亡风险。MELD 与 PELD公式简单、客观、可以证实，无论什么时候计算评分，都可以得到一致结果。
OPTN/UNOS委员会在MELD 与 PELD基础上提出了供肝利用政策，主要是帮助移植患者或家庭申请者。其由OPTN/UNOS指导委员会在2001年11月批准，从2002年2月开始使用。

How are livers offered through MELD and PELD?
Livers are offered first to urgent and compatible patients in the donor’s local
area (often defined as a state or large metropolitan area), then to a larger region
of the country (the OPTN/UNOS has 11 allocation regions in the U.S.), then
nationwide. Because Status 1 candidates are most medically urgent, each liver
is first offered to local Status 1 candidates, then regional Status 1 candidates.
The sequence of offers after Status 1 patients depends on the donor’s age.
If the donor is younger than 18, after any Status 1s are considered the liver
would next be offered to candidates in the region age 11 or younger. The
organ would then be considered for local and then regional candidates with
a MELD of 15 or higher. Any patients age 12 to 17 would be considered
ahead of adult patients.
If the donor is 18 or older, the liver would be offered first to local and
regional Status 1 candidates. If not accepted for any of these patients, the
liver is then offered to candidates with a MELD/PELD score of 15 or higher,
first locally and then regionally.
If the liver is not matched to any candidates with a MELD/PELD of 15 or
higher, it may then be considered for local, then regional candidates with a
MELD/PELD of 14 or less. Finally the liver would be offered for any compatible
candidates nationwide, beginning with Status 1 candidates and then to
those with the highest MELD/PELD scores.

肝脏怎样通过MELD 和PELD提供
肝脏首先要给与那些供体本地区内（常定义为一个州或者大的城区）的紧急和配型合适的患者，然后才是该国家更大的区域（OPTN/UNOS在美国有11个分配区域），最后才是全国。由于第一种患者的情况非常紧急，每个肝脏首先要提供给本地的该患者，然后是本区域的此类患者。在此类患者之后，提供的顺序要根据供体的年龄决定。如果供体年龄小于18岁，在任何第一种情况的患者之后，接下来应该提供给此区域内年龄小于11岁或更小的患者。然后该器官再考虑给那些 MELD〉=15、且先本地后区域的患者。应该在考虑成年患者之前，优先考虑那些年龄在12到17岁的患者。如果供体年龄〉=18岁，肝脏应该首先给本地和地区的第一种情况的患者。如果这些患者没有一个能够使用，然后该器官再考虑给那些MELD〉=15、且先本地后区域的患者。如果这个肝脏不适合任何 MELD〉=15的患者，它就可以考虑给那些MELD<=14、且先本地后地区的患者。最后，这个肝脏可以提供那些全国配型合适的任何患者，首先是第一种情况的患者，然后是那些MELD/PELD评分最高的患者。

How is waiting time counted in the system?
Various studies report that waiting time is a poor indicator of how urgently
a patient needs a liver transplant. This is because some patients are listed
for a transplant very early in their disease, while others are listed only when
they become much sicker.
Under the MELD/PELD system with a wide range of scores, waiting time is
not often used to break ties. Waiting time will only determine who comes
first when there are two or more patients with the same blood type and the
same MELD or PELD score.
If a patient’s MELD or PELD score increases over time, only the waiting time
at the higher level will count. (For example, if you have waited 40 days with
a score of 12, and 5 days with a score of 15, you would only get credit for 5
days of waiting time at the score of 15.) However, if the patient’s MELD or
PELD score decreases again, he or she would keep the waiting time gained
at the higher score. (Using the earlier example, if your score goes from 12
to 15 and back to 12, you would have 45 days of waiting time at the score of
12.) Patients initially listed as a Status 1 also keep their waiting time if their
condition improves and they later receive a MELD/PELD score.
Patients with higher MELD/PELD scores will always be considered before
those with lower scores, even if some patients with lower scores have waited
longer. (For example, a patient waiting for one day with a score of 30 will
come ahead of a patient with a score of 29, even if the patient with a 29 has
waited longer. This is because the patient with a score of 30 has a higher
risk of dying without a transplant.)

该系统的等待时间怎样计算？
多种研究报道，等待时间对一个急切需要肝移植的患者是一个很差的指标。这是因为，一些患者在疾病的早期就被列入了移植名单，而其他被列入名单的，仅仅是因为他们患了很严重的疾病。MELD/PELD有一个大范围的评分，等待时间不会经常用来打破常规。等待时间仅仅决定了谁先来做，当有两个或更多的患者是同种血型并且MELD 和PELD评分相同。如果一个患者的MELD 或PELD随着时间增加，那么等待时间就会在一个更高的基础之上开始计算。（例如，如果你的评分是12等待了40天，15分等待了5天，那么你的分数是 15时，你仅仅得到了5天等待时间的分值？？）但是，如果这个患者的MELD 或PELD又下降了，其将保持较长时间的等待。（仍然利用前面的例子，如果你的分数从15降到了12，那么你的等待时间将是12分时的45天）。那些最初被列入第一种情况的患者，如果其状况得到改善，也将等待并且重新进行MELD/PELD评分。具有较高MELD/PELD评分总会比那些评分较低的患者优先考虑，即使一些分数较低的患者等待了更长的时间。（例如，一个等待了一天、评分30的患者，也会在评分29患者之前，即使该患者等待时间更长。这是因为，评分30的患者如果不行肝移植，其死亡风险会更高）

What if I had been on the waiting list when the system changed?
For the first year of the MELD and PELD system, a transition plan was in place
for liver candidates awaiting a transplant at the time of the change to maintain
their priority gained under the previous policy. After the transition period
ended, those candidates still awaiting a transplant were prioritized only by
their MELD or PELD score.
If you were listed for transplant at the time the policy became effective
(February 27, 2002), your transplant team would best be able to address any
questions about the transition and/or your current medical status.
All patients newly listed for a liver transplant since February 2002 receive
priority only by their MELD or PELD score, based on their current lab results.
Do MELD and PELD account for all conditions?
MELD/PELD scores reflect the medical need of most liver transplant candidates.
However, there may be special exceptions for patients with medical conditions
not covered by MELD and PELD. If your transplant team believes your case
qualifies for an exception, they may submit information to a review board
and request a higher score. The review board will consider the medical facts
and determine whether or not to grant a higher score.
Is this system likely to change?
Liver allocation policy based on MELD and PELD has already been changed
as transplant professionals have applied and learned from the system, and
future changes will likely be required to better meet patients’ needs. In fact,
this system is designed to be flexible and allow improvements. In transplantation,
as in all scientific fields, new studies are taking place all the time to learn how
to save more lives and help people live longer and better.
MELD/PELD Calculator Documentation
The MELD/PELD Calculator is a utility that allows you to enter hypothetical or actual parameters and calculate a MELD or PELD score for an individual patient.
The MELD/PELD Calculator provided on this site uses the specific formulas approved by the OPTN/UNOS Board of Directors and used for the allocation of livers by the OPTN match system.
The MELD score calculation uses:
Serum Creatinine (mg/dl) **
Bilirubin (mg/dl)
INR
**For patients who have had dialysis twice within the last week, the creatinine value will be automatically set to 4 mg/dl.
The MELD Calculator is used for patients who are 12 years and older. After entering
the laboratory values,you may calculate the score by clicking Calculate. The MELD score displays in the MELD Score field.You can also calculate a score by simply tabbing into the MELD Score field.
The PELD score calculation uses:
Albumin (g/dl)
Bilirubin (mg/dl)
INR
Growth failure (based on gender, height and weight)
Age at listing

The PELD Calculator is used for patients who are under 12 years old. After entering the laboratory values,you may calculate the score by clicking Calculate. The PELD score displays in the PELD Lab Value field. You can also calculate a score by simply tabbing into the PELD Lab Value field.
MELD Formula
The MELD score is calculated using the following formula:
MELD Score = 0.957 x Loge(creatinine mg/dL)
+ 0.378 x Loge(bilirubin mg/dL)
+ 1.120 x Loge(INR)
+ 0.643?
Multiply the score by 10 and round to the nearest whole number.
Laboratory values less than 1.0 are set to 1.0 for the purposes of the MELD score calculation.
The maximum serum creatinine considered within the MELD score equation is 4.0 mg/dl (e.g. if you enter
4.3 for serum creatinine the formula will calculate 0.957 x Loge(4.0) for the serum creatinine portion of the
MELD formula).
If you answer Yes to the question: “Had dialysis twice within a week prior to Serum Creatinine test?” then
the MELD score will be calculated with a serum creatinine value of 4.0 mg/dl. For example, if you enter
3.0 for serum creatinine and answer Yes to the dialysis question, then the formula will calculate 0.957 x
Loge(4.0) for the serum creatinine portion of the MELD formula.
PELD Formula
The PELD score is calculated using the following formula:
PELD Score = 0.480 x Loge(bilirubin mg/dL)
+ 1.857 x Loge(INR)
- 0.687 x Loge(albumin g/dL)
+ 0.436 if patient is less than 1 year old (scores for patients listed for liver transplantation
before the patient's first birthday continue to include the value assigned for age (< 1
Year) until the patient reaches the age of 24 months)
+ 0.667 if the patient has growth failure (<-2 Standard deviation)
Multiply the score by 10 and round to the nearest whole number.
Laboratory values less than 1.0 are set to 1.0 for the purposes of the PELD score calculation

MELD/PELD评分产生背景

美国的早期肝移植标准首先是根据患者住院清况来确定肝移植先后顺序的.在重症监护病房(工CU)中的患者优先得到肝移植，其次是住在普通病房中的患者，再次是那些不需住院的患者，这种宽泛的分类方式造成每一组中都有很多患者争夺有限肝源的情况，只好以等待时间的长短来确定肝移植的顺序。这种情况使一部分肝功能代偿良好的患者优先得到了肝移植而一些晚期肝病患者却失去了肝移植的机会，肝移植中的不合理现象很常见。
1997年，U NOS根据病情将患者分成病情1、2A, 2B和3四类情况，后三类是以CTP评分为基础的。暴发性肝病、首次移植肝在1周内无功能和血管血栓形成、或儿童患者需持续在ICU中监护者为病情1，病情2A是指慢性肝病患者的CTP分值>=10,需ICU监护和患者生存期预计小于7d的患者，以上患者被列为肝移植的首选对象;病情2B是指慢性肝病患者CTP分值>=0,存在腹水、肝性脑病等并发症或原发性肝癌无转移患者;病情3是指CTP分值最少应大于7，病情较稳定的患者。这种分类仍有很大的局限性，每一类当中仍存在许多分值相同的患者，实际上等待时间的长短仍是决定肝移植的关键因素，况且CTP中存在着固有缺陷，其中最主要的是使用了两个主观指标即肝性脑病和腹水，因此CTP评分具有较大的随意性和主观性，这不符合公平、公正、透明的移植原则。

MELD分级的优点:
与CTP分级相比较，MELD分级有以下优点:首先，MELD分级中无腹水、肝性脑病等主观性指标。MELD分级中的二个指标均以客观的实验室检查作为依据，惟一需人为解释的指标是病因，但去掉病囚后，对MELD分级的功能并无明显影响其次，CTP分级把病情限定在10分的狭窄分级范围之内，不可避免的存在同一分级中有很多分值相同的患者，在这种情况下，只有把等待时间作为筛选肝移植患者的标准。而MELD分级中，MELD分值无“底”和“顶”现象，评价病情的范围增宽了，且分值是连续的，因此，能较好的区分出病情的轻重;第三，CTP分级中使用的蛋白质和凝血酶原时间等指标在各个国家和地区甚至在同一地区的不同实验室之间差别很大，而MELD分级中使用的三个指标在各实验室之间差别并不是很大，而且易获取、可以重复测定。另外，CTP分级是由创造者根据临床经验总结所得，而MELD分级是由前瞻性分析统计资料所得，因而具有更好的预测作用。（来源美国器官移植共享网）

[ 本帖最后由 liver411 于 2009-2-7 10:48 编辑 ]

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