2007年11月6日（奥兰多）——密西根大学的Robert Merion博士在美国肝病研究协会第58届年会上指出，移植外科医生面对的关键挑战是怎样把得到的肝脏移植给真正适合的患者。

Merion博士说，由于供体群趋于老龄化，“扩大标准”已经变得更加普遍了。这些器官将使移植失败和死亡的风险更大，因此，外科医生需要考虑怎样才能够整合供体的风险，以及如何使患者获得更好的移植疗效。

Merion博士说，每年约有2000名患者在等待肝移植的时候死亡。等待期死亡事件依然使我们不得不考虑使用不太理想的供体肝脏。”

Merion博士说与过去相比，现在大多数的捐赠者年龄都在50岁以上，且大部分捐赠者都死于中风或心血管疾病。目前捐赠的肝脏中，大约一半都来自于中风死亡的捐赠者，他们的器官使移植失败的风险升高了约15%。

Merion博士称，现在的问题不是患者想要一个怎样合适的脏器，问题是在脏器来源如此紧缺的时期，患者面对一个不是很合适的、高风险肝脏，是选择移植，还是继续等待更合适的、低风险的供体肝脏。

他采用一种“移植获益”的范例来分析这个问题，该范例同时考虑接受特殊脏器移植的益处，以及继续等待另一个供者危险指数(DRI) 较好的脏器的益处及危险度。Dr. Merion在报告中还考虑到如果患者拒绝了这个不太合适的脏器，那么以后有可能不会再碰到比它更合适的脏器了。

Merion说，对于MELD分值较低的患者，与其接受一个高风险的器官，不如继续等待另一个更合适的肝脏。MELD系统是一种评估肝病患者死亡风险的评分方法，美国从2001年起开始采用这种方法来分配器官。

他说：“通常人们都认为风险高的脏器更适合低风险的患者，实际上“移植获益”范例并不支持这一观点。”

从移植获益的角度考虑， MELD分值最高、病情最严重的患者，更适宜接受高危供者的肝脏，而不应该继续等待更合适的供肝。Merion说到：“一些外科医生已经开始考虑所有这些因素了。”

他说：“在临床实践中，当我们在半夜必须做出是否采用某一特殊脏器时，我们实际上考虑的是移植后的实际疗效，并以此来判断某个特定患者是否应该接受该器官。这并不是我们规则系统的一部分，也不是脏器分配系统的组成部分，而且我们一般也不会谈论到它。”
Merion博士说，研究人员在开发评估尸体供肝风险和预测受体移植益处的方法时，需要在一个“公开而透明的态度”下利用这些因素。

Douglas Hanto博士是AASLD管理委员会的成员之一，同时也是马萨诸塞州波士顿Beth Israel Deaconess医学院的一名移植外科医生。Hanto博士表示，移植外科医生们花费了大量的时间试图找出与移植术后疗效有关的风险因素，目前已经取得了一定进展，并且Merion博士正试图进行更进一步的研究。

Hanto博士说：“他正设法识别怎样才能在了解患者和捐赠者的同时，更好的预测单个病例的获益。”他还指出到目前为止，2006年开发的供者危险指数(DRI)还没有被常规应用。“我们知道DRI的存在，我们也会想到它。但是，我们把它应用到每一位供体身上了吗？事实上我们并没有这样做。”

临床实践应用重点：
--与过去相比较大多数供肝者都大于50岁，大多数人死于中风和心血管疾病，其中有一半的供肝者来自死于中风的患者，这使肝移植失败的风险提高了15%。
--根据肝移植获益的范例分析， MELD的分值最高病情最严重的患者，与等候合适移植肝的MELD分值低的低危患者相比较，接受高危供体的移植肝可能更受益。

Donor Risk Must Be Factored Into Transplant Decisions
November 6, 2007 (Orlando) — The key challenge facing transplant surgeons is how to get the right liver into the right patient, according to Robert Merion, MD, from the University of Michigan, who spoke here at the American Association for the Study of Liver Diseases (AASLD) 58th Annual Meeting.

Because the donor pool is aging, the use of "expanded criteria" donor livers has become more common, Dr. Merion said. These organs come with higher risk of graft failure and death, so surgeons need to think about how to better incorporate donor risk into their thinking about how to offer the best transplantation services to patients, he added.

About 2000 patients die on the waiting list each year, Dr. Merion said, adding that "liver waiting list deaths continue to drive a use of livers that we might consider to be less than ideal."

Donors are more likely to be older than 50 years now than in the past and are more likely to have died of stroke or cardiovascular disease, Dr. Merion said. About half of all donor livers now come from patients who died from stroke, even though risk of failure is 15% higher for their organs.

Rather than ask how a patient will do with a particular organ, the question may be instead how a patient will do with that organ compared with waiting for a lower-risk organ to come available, according to Dr. Merion.

He uses a "transplant benefit" paradigm that looks at both the benefit of accepting a particular organ and the benefits — and risks — of waiting for another organ with a better donor risk index (DRI). Dr. Merion's approach takes into account that a suitable organ may not become available again to patients who turn them down.

Often, patients with low Model for End-stage Liver Disease (MELD) scores were better off waiting for another organ than accepting a high-risk organ, Dr. Merion said. MELD is a measure of mortality risk for people with liver disease that has been used to allocate organs in the United States since 2001.

"The conventional wisdom that high-risk organs are more appropriate for low-risk patients really doesn't hold up under the transplant benefit paradigm," he said.

By looking at transplant benefit, the sickest patients with the highest MELD scores were more likely to benefit from a transplant with a high-risk donor than from waiting. "Some surgeons already consider all these factors informally," Dr. Merion said.

"In practice, when we make decisions about particular organ offer in the middle of the night, we're actually considering what the actual posttransplant benefit will be and factoring that into the equation about whether or not to accept an organ for a given patient," he said. "It's not officially a part of our algorithm, it's not an official part of our allocation system, and we mostly don't talk about it."

As researchers develop tools to both assess the risks of deceased donor liver and calculate transplant survival benefit for recipients, researchers need to use them in an "open and transparent manner," Dr. Merion said.

Transplant surgeons have spent a lot of time trying to figure out risk factors for transplant outcomes, said Douglas Hanto, MD, PhD, a member of the AASLD governing board and a transplant surgeon at Beth Israel Deaconess Medical School in Boston, Massachusetts. There has been progress, and Dr. Merion is trying to take that one step further, Dr. Hanto said.

"He's trying to identify how...we predict benefit in an individual patient knowing that patient and knowing the donor," Dr. Hanto said.

As of now, the DRI, which was developed in 2006, is not in routine use, he noted. "It is there, it's of interest, we know about it, we think about it," he said. "But, do we use it and apply to every donor We don't really."

Dr. Merion has disclosed no relevant financial relationships

[责任编辑:刘聪]