協助預測肝臟移植後存活率之模式


  November 3, 2006 — 根據一項發表於11月號肝臟移植期刊的研究指出,當肝臟是來自特定捐贈者、特別是高風險捐贈者,一個新的模式或許可以協助預測肝臟移植後存活率,該模式可能可以預測移植後存活之時間長短。
  
  來自華盛頓西雅圖後備軍人事務Puget Sound健康照護系統的George N. Ioannou與其同事表示,增加肝臟移植器官機會的方式是放寬挑選肝臟捐贈者的條件。
  
  Ioannou醫師表示,不幸的,目前並沒有大家一致認同的捐贈條件,相對的,個別的肝臟移植系統使用不同且通常是以定義不清的條件來決定捐贈者是否適合進行肝臟移植,這樣的條件包括捐贈者年齡、是否有高風險行為、肝臟切片顯示之脂肪變性程度、冷凍缺血時間、活體外時間以及肝臟巨觀。
  
  這項試驗的目的在於發展且驗證一個根據移植前捐贈者以及受贈者狀況,以預測病患接受肝臟移植後存活率的模式;聯合器官共享網絡收集於1994年至2004年間在美國接受肝臟移植病患資料,總共有6,477位病患感染C型肝炎病毒(HCV),透過比例風險迴歸模式,研究者找出一個最能夠預測存活率的捐贈者與受贈者特徵,並將這些特徵納入多變項模式中。
  
  排除條件包括10歲以下、75歲以上捐贈者、活體捐贈者、部分肝臟捐贈者、心跳停止捐贈者、血清鈉濃度高於170 mmol/l以上的捐贈者、多重器官捐贈者、過去已捐贈過器官病患、以及資料不全者。
  
  最能夠預測肝臟移植後存活率的特徵,包括是否感染HCV,該模式利用4種捐贈者特徵(年齡、冷凍缺血時間、性別、以及種族/宗教),以及9種受贈者特徵(年齡、身體質量指數、末期肝臟疾病嚴重度指標、聯合器官共享網絡病況指標、性別、種族/宗教、糖尿病、肝臟疾病成因、與血清白蛋白濃度);HCV感染病患所使用的模式些微不同,同樣的捐贈者特徵、所有受贈者的特徵,除了肝臟疾病成因與血清白蛋白濃度。
  
  作者表示,該模式突顯了捐贈者與受贈者特徵對於移植後存活的影響很大,這裡所提出的模式或許可以轉化為分數,以可能的捐贈者、受贈者、捐贈者/受贈者組合等變項,來評估器官移植後器官功能喪失的風險;該模式或許可以用為當已有特定捐贈者告知肝臟移植候選人以及醫師,移植後的存活率有多少,對中度風險與高風險捐贈者來說是特別有意義的。
  
  試驗限制包括無法校正每個移植中心的差異、無法確認資料的正確性、排除資料不足的病患,以及在研究進行的10年間,預測存活率的變數可能改變的誤差。
  
  作者的結論是,最終,以這個模式決定風險指數以及預測存活率可能是一個評估特定活體捐贈者、受贈者或是捐贈者/受贈者組合風險較客觀的方式;如果同時有2位捐贈者,預測存活率較低的受贈者接受預測存活率較高的捐贈者是比較適當的,反之亦然,因為這樣可以使這兩種受贈者的移植後存活率相當。
  
  美國腸胃醫學會青年學者發展獎、退伍軍人事務西北C型肝炎資源中心、退伍軍人事務Puget Sound健康照護系統研究增益獎計畫以及健康資源與服務部門協助贊助該研究。
  
  在隨後的評論中,來自賓州費城Thomas Jefferson大學醫院Ignazio R. Marino醫師建議,應該進行以肝臟移植者為對象的大型前瞻性試驗,來協助改善分配條件、並且定義模式中未來的捐贈者不會被誤認為受贈者。
  
  Marino醫師表示,如果肝臟移植候選人可以在器官分派時被分為不同的風險類別,不可避免的問題將會發生,我們應該試著尋找合適捐贈者以及受贈者嗎?除此之外,我們應該試著評估病患是否太虛弱而不適合接受移植,並且建立統一的排除條件?目前為止,我們可能對於配對尚未準備完全,但是這措施將會是我們的最終目標。

Model May Help Predict Surviva

By Laurie Barclay, MD
Medscape Medical News

November 3, 2006 — A new model may help predict survival after liver transplant, according to a report in the November issue of Liver Transplantation. The model may predict the length of posttransplant survival when a given donor is offered and may be particularly helpful for marginal or high-risk donors.

"One way to increase the availability of organs for liver transplantation is to expand the criteria that are used to determine whether an organ from a potential liver donor is acceptable for liver transplantation," write George N. Ioannou, from the the Veterans Affairs Puget Sound Health Care System in Seattle, Washington, and colleagues.

"Unfortunately, no such universally accepted criteria exist," according to Dr. Ioannou. "Instead, individual transplant programs use different, and often poorly defined, criteria to determine whether to use the liver of a potential liver donor for transplantation. Such criteria include donor age, donor high-risk behavior, the degree of steatosis on liver biopsy, cold ischemia time, down time, and the macroscopic appearance of the liver."

The objective of this study was to develop and validate a comprehensive model that predicts survival after liver transplantation, based on pretransplant donor and recipient characteristics. The United Network for Organ Sharing had complete data available for 20,301 patients who underwent liver transplantation in the United States between 1994 and 2003, including 6477 patients infected with hepatitis C virus (HCV). Using proportional-hazards regression, the investigators identified the donor and recipient characteristics that best predicted survival and incorporated these characteristics in a multivariate model.

Exclusion criteria were patients who had donors younger than 10 years or older than 75 years, living donors, split-liver donors, non–heart beating donors, donors with serum sodium concentration greater than 170 mmol/L, as well as patients with multiple organ transplants, previous liver transplants, and incomplete information.

To best predict survival after liver transplantation in patients without HCV infection, the model used 4 donor characteristics (age, cold ischemia time, sex, and race/ethnicity) and 9 recipient characteristics (age, body mass index, model for end-stage liver disease score, United Network for Organ Sharing priority status, sex, race/ethnicity, diabetes mellitus, cause of liver disease, and serum albumin). A slightly different model was used for patients with HCV infection, including the same donor characteristics, and all recipient characteristics except cause of liver disease and serum albumin.

"The models illustrate that variations in both pretransplant donor and recipient characteristics have a large effect on posttransplant survival," the authors write. "The models presented here can be used to derive scores that are proportional to the excess risk of graft loss after liver transplantation for potential donors, recipients, or donor/recipient combinations. The models may be used to inform liver transplant candidates and their doctors what posttransplant survival would be expected when a given donor is offered and may be particularly helpful for marginal or high-risk donors."

Study limitations include inability to adjust for each individual center; inability to verify the accuracy of the data; exclusions of persons with missing data; and the possibility that predictors of survival might have changed slightly during the 10-year study period.

"Ultimately, risk scores and predicted survivals determined from such models may be an objective
way to assess the risk of a given liver donor, recipient, or donor/recipient combination," the authors conclude. "If two donors are expected to be available at approximately the same time, it would be more equitable for the recipient with worse predicted post-transplant survival to receive the donor with the better predicted survival and vice versa since that would make the post-transplant survival of the two recipients more similar."

The American College of Gastroenterology Junior Faculty Development Award, Veterans Affairs Northwest Hepatitis C Resource Center, Veterans Affairs Puget Sound Health Care System Research Enhancement Award Program, and the Health Resources and Services Administration helped fund this study.

In an accompanying editorial, Ignazio R. Marino, MD, FACS, from the Thomas Jefferson University Hospital in Philadelphia, Pennsylvania, recommends a large prospective study of liver transplant candidates to help optimize allocation criteria and to define when a prospective donor should not be used for a prospective recipient.

"If candidates for [liver transplant] can be stratified into different risk categories at the time of the actual organ allocation, the inevitable question arises: Should we try to match donors and recipients?" Dr. Marino writes. "In addition, should we try to implement rules to assess when a patient is too sick for [liver transplant] and have uniform delisting criteria?.... We might not be ready to match donors and recipients yet, but this procedure should be our ultimate goal."

Liver Transplantation. 2006;12(11):1574-1576, 1594-1606

    
相關報導
社工在C型肝炎治療中的角色
2014/3/26 上午 10:55:04
C型肝炎:有效的6種預防策略
2013/7/31 上午 10:19:22
異性伴侶之間的C型肝炎傳染很罕見
2013/3/27 上午 10:00:41

上一頁
   1   2   3   4   5   6   7   8   9   10  




回上一頁