荷蘭活體腎臟互換計畫有高成功率


  January 11, 2007 — 荷蘭的一個國際互換計畫發現,146對活體腎臟成功配對49%,且捐贈者和受贈者間的血型不符或者交叉配對陽性;這個計畫是從2004年開始,30個月的結果在2006年12月27日的Transplantation期刊發表。
  
  該研究的主要作者、Erasmus醫學中心的Marry de Klerk醫師向Medscape表示,包括人類白血球抗原[HLA]實驗室在內的七個大學移植中心滿腔熱血的合作下,有許多的參與者,得到一個如此傑出的成功率。
  
  【有意願但未配對成功的捐贈者】
  該團隊指出,過去卅年來,在荷蘭平均等待腎臟移植的時間從不到1年增加到4 –5年,活體腎臟捐贈的接受度和以腹腔鏡手術切除捐贈者腎臟的發展,增加了此手術方式的吸引力;但是有些移植候選人和潛在的活體腎臟捐贈者的ABO血型不相容,或者對捐贈者的HLAs有抗體(敏感),導致呈現交叉配對陽性;病患或許可以有較高的敏感度—較高的陪審反應抗體(PRA) — 歸因於輸血、懷孕或者曾有過移植;對於這些病患,可在免疫球蛋白治療後使用血漿析離術或免疫吸附法以移除抗體。
  
  一個較不貴的策略是一個配對捐贈者腎臟互換計畫,舉例來說,兩個不相容的捐贈者受贈者配對,將其中一對的腎臟給另一對的移植候選人,反之亦然;在荷蘭,全部七個腎臟移植中心在2004年開始這樣的計畫,該文檢視了30個月的結果。
  
  從2004年1月直到2006年6月,共有146對不相容的捐贈者受贈者配對參加活體腎臟互換計畫;(de Klerk醫師指出,不相容的捐贈者受贈者配對沒有選擇不參加的);受贈者平均年紀為51歲(範圍從15 – 73歲),且在屍腎移植等待名單上平均等待13個月 (範圍從0 – 172 個月);捐贈者平均年紀為 52 歲 (範圍從26 – 77歲);捐贈者受贈者配對中,69位移植候選人(48位女性和21位男性)和他們的潛在捐贈者有交叉配對陽性,77位移植候選人(31位女性和46位男性) 和他們的潛在捐贈者的 ABO血型不相容,捐贈者身份最多的是配偶(86/146, 59%)。
  
  每三個月,參加者可以註冊進行電腦配對,在研究期間,進行10個配對步驟(合併 2對捐贈者受贈者配對,2005年之後則是合併最多3對捐贈者受贈者配對);分配規範是血型(先確定血型然後看有無相容)、配對機率(受贈者找到捐贈者的最低機會,若和捐贈者間ABO 血型相容和可接受HLA抗原,就排在第一順位)、等待時間,以及捐贈者年紀;七個移植中心有一個共通規範,規定捐贈者來到受贈者的中心和接受手術必須是自願的。
  
  【高成功率】
  基於ABO血型和不能接受HLAs的配對,為122 捐贈者受贈者配對鑑別了1019種可能的配對,其他24對沒有潛在的解決方法;配對機率篩選基礎得到72種新的配對組,此成功率在交叉配對陽性組顯著高於ABO血型不相容組。
  
  不相容的捐贈者受贈者配對之成功配對

交叉配對陽性組

ABO 血型不相容組

P

44/69

28/77

.0015


  三次嘗試後,兩種類別找到新捐贈者的機會變得微乎其微,這兩組,PRA均影響成功率,但那些有較高敏感度的病患還是可以得到幫助。
  
  不是O對O血型者難以配對,不過, 這之中有9/53 (17%) 配對組是在交叉配對陽性組,得到18件移植 ;該團隊指出,這顯示合併這兩類的捐贈者受贈者配對增加了配對受贈者互換計畫的效果。
  
  72對配對組中,已經進行57件移植,5件已在計畫中。
  
  他們結論表示,配對活體腎臟互換是絕佳的解決方案,且是這些因為ABO血型或交叉配對不相容而無法找到相容捐贈者的病患的第一優先選擇,對於無法找到合適配對的「不幸的一對」,的確需要替代的策略。
  
  de Klerk 醫師表示,此一解決方案的訊息是捐贈者受贈者配對不相容的首選,此計畫仍在進行中, 且他們對三年來的結果感到高興。

Dutch Living Donor Kidney Exch

By Marlene Busko
Medscape Medical News

January 11, 2007 ??A national exchange program in the Netherlands found successful matches for 49% of 146 living kidney donor-recipient pairs who had incompatible blood types or positive crossmatches. These 30-month results from a program embarked on in 2004 are reported in the December 27, 2006 issue of Transplantation.

"The full-hearted cooperation between 7 university transplant centers, including their [human leukocyte antigen] HLA laboratories, has resulted in a high number of participants, which is absolutely necessary for such an excellent success rate," the study's lead author, Marry de Klerk, MD, from the Erasmus Medical Center, in Rotterdam, the Netherlands, told Medscape.

Willing but Mismatched Donors

The group writes that in the Netherlands, over the past 3 decades, the median wait time for a kidney transplant has increased from under 1 year to 4 to 5 years. The favorable outcome of living kidney donation and the development of laparoscopic donor nephrectomy have increased the attractiveness of this procedure. Yet some transplant candidates and potential living kidney donors have either incompatible ABO blood types or have antibodies (are sensitized) to donor HLAs, resulting in a positive crossmatch. Patients might have a high level of sensitization ??a high panel reactive antibody (PRA) ??due to transfusions, pregnancy, or previous transplants. A protocol of using either plasmapheresis or immunoabsorption to remove the antibodies, followed by immunoglobulin therapy, has been used for such patients.

A less expensive strategy is a paired donor kidney exchange program, where, for example, 2 incompatible donor-recipient pairs are matched so that the kidney from one pair is given to the transplant candidate in the second pair, and vice versa. In the Netherlands, all 7 kidney transplant centers embarked on such a program in 2004. This article examines the 30-month results.

From January 2004 until June 2006, 146 incompatible donor-recipient pairs participated in the living donor kidney exchange program. (No incompatible donor-recipient pairs chose not to participate, Dr. de Klerk said.) Recipients had a median age of 51 years (range, 15 ??73) and had been on a cadaveric kidney transplant wait list for a median of 13 months (range, 0 ??172 months); donors had a median age of 52 years (range, 26 ??77). Of the donor-recipient pairs, 69 transplant candidates (48 women and 21 men) had a positive crossmatch with their potential donors, and 77 transplant candidates (31 women and 46 men) had an ABO blood type that was incompatible with their potential donors. The largest donor group consisted of partners (86/146, 59%).

Every 3 months, the participants could be registered for a computer match; during the study period, 10 match procedures were performed (combinations of 2 donor-recipient pairs until 2005, and combinations of up to 3 donor-recipient pairs since then). Allocation criteria were blood type (first identical and then compatible), match probability (the recipient with the lowest chance of finding a donor, based on compatible ABO type and acceptable HLA antigens within the donor population, was ranked first), wait time, and donor age. The 7 transplant centers had a common protocol that prescribed that the donor travel to the recipient's center and the surgical procedures take place simultaneously.

High Success Rate

Matching based on ABO blood types and unacceptable HLAs identified 1019 possible matches for 122 donor-recipient pairs, with no potential solutions for 24 pairs. Selection on the basis of match probability resulted in 72 new match combinations. The success rate was significantly higher in the positive-crossmatch group than in the incompatible-ABO-blood-type group.

Successful Matches Among Incompatible Donor-Recipient Pairs

Positive-Crossmatch Group
Incompatible-ABO-Blood-Type Group
P
44/69
28/77
.0015

After 3 attempts, the chance of finding a new donor in both categories of patients became remote. In both groups, PRA influenced the success rate, but a substantial number of highly sensitized patients could still be helped.

The blood type non-O-to-O combination was difficult to match. However, for 9/53 (17%) of these couples, matching couples were found in the positive-crossmatch group, allowing 18 transplants to be made. "This demonstrates that combining 2 categories of donor-recipient pairs increases the efficiency of a paired donor exchange program," the group writes.

From the 72 matched pairs, 57 transplants have already been performed, and 5 procedures are planned, the team writes.

They conclude: "Paired living donor kidney exchange is an excellent solution and the first choice for a substantial number of recipients who cannot identify a compatible donor because of an ABO-blood-type or crossmatch incompatibility." For "unlucky couples" for whom a suitable match cannot be found, alternative strategies need to be explored, they add.

"The message is that logistic solutions should be the first option for incompatible donor-recipient combinations," Dr. de Klerk said, adding that the program is ongoing and they are happy with the 3-year results.

Transplantation. 2006;82:1616-1620.

    
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