UNOS DonateLife

May 17, 2013

UNOS Researchers Present Studies at American Transplant Congress

Seattle -- United Network for Organ Sharing (UNOS) staff members authored and will present several studies at the American Transplant Congress (ATC), a joint meeting of the American Society of Transplant Surgeons and the American Society of Transplantation held May 18-22 at the Washington State Convention and Trade Center. UNOS staff members are primary authors of a total of nine papers.

NOTE: Some of these studies were supported wholly or in part by Health Resources and Services Administration contract 234-2005-370011C. The content is the responsibility of the authors alone and does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Below is a listing of studies in which UNOS researchers are primary authors. UNOS staff researchers are indicated with an asterisk.

An Early Look at the OPTN Explant Pathology Form Data
Embargo until Sunday, May 19 – 3:27 p.m. PDT
Authors: Ann M. Harper*, Erick B. Edwards, Ph.D.*, Julie K. Heimbach, M.D., Ryutaro Hirose, M.D., Richard B. Freeman, M.D., Kim M. Olthoff, M.D.

Liver transplant candidates with hepatocellular carcinoma (HCC) are eligible to receive an exception that will increase their allocation score above the calculated MELD/PELD formula used for most liver transplant candidates. To ensure that this priority is appropriate, centers must submit the recipient’s explant pathology form to UNOS to confirm the diagnosis of HCC. Beginning in 2002, these forms were faxed to UNOS, making compliance monitoring and analysis of the information difficult. As of April 2012, these forms are now submitted via an on-line form.

Based on data submitted on forms to date, the vast majority of recipients who received an exception score for HCC had evidence of HCC in the explanted liver. The great majority of recipients had received pre-transplant treatment for HCC. Of those who met the standard criteria for an HCC exception, only 20 percent had tumors that exceeded these criteria when the removed liver was examined by a pathologist. As more data become available, additional research will be valuable to compare post-transplant outcomes based upon pre-transplant treatment, as well as the stage and differentiation of the tumors.

The U.S. Experience in ABO Incompatible Pediatric Heart Transplantation
Embargo until Sunday, May 19 – 4:00 p.m. PDT
Authors: Wida S. Cherikh, Ph.D.*, Leah B. Edwards, Ph.D.*, Marissa A. Clark, M.S.*, Chad Waller, M.S.*, David M. Campbell, M.D., Yulin Cheng*, Steven A. Webber, M.B., Ch.B., MRCP

A policy implemented in 2010 allows Status 1A and Status 1B (medically urgent) pediatric candidates younger than age two at the time of listing who meet certain eligibility requirements to accept a heart of any blood type, including those normally considered incompatible. Previous experience has indicated that infants are able to be transplanted with a heart of any blood type due to their immature immunologic systems. The researchers studied candidates listed for and transplanted with hearts of any blood type since the policy was implemented.

Of all the Status 1A and Status 1B registrations added to the heart waiting list prior to their second birthday, 36 percent indicated at listing a willingness to accept a heart of any blood type. The great majority of these candidates were listed in the most urgent medical status (1A). In the two years following policy implementation, 26 blood type incompatible heart transplants were performed; of those, 25 were for Status 1A recipients less than one year old and one was for a Status 1B recipient between the age of one and two. Six-month patient survival for these recipients (96 percent) was comparable with that of similar recipients with a blood type identical or compatible transplant (89 percent). Early results support transplanting infants with hearts of any blood type. More data is needed to assess the experience of candidates older than one year of age, as well as longer-term survival and other outcomes for the recipients of incompatible blood type transplants.

Follow-Up Reporting for Living Kidney Donors
Embargo until Monday, May 20 – 2:27 p.m. PDT Authors: Jennifer L. Wainright, Ph.D.*, Maureen A. McBride, Ph.D.*, Mary Amanda Dew, Ph.D., D. Lee Bolton, RN*, Christie P. Thomas, M.B., FRCP, FASN, FAHA

To help assess short-term risks of living kidney donation, timely and detailed follow-up reporting of living donor outcomes is very important. The researchers studied trends in donor follow-up reporting of laboratory and clinical data for all living kidney donors who donated in the United States from 2007 through 2010, excluding those whose kidney was not transplanted at the same hospital where it was recovered.

Rates of reporting increased over the study period for both timely clinical and lab data. For those who donated in 2010, 48 percent had timely clinical reporting and 32 percent had timely lab data. Very few reports were not submitted due to living kidney donors declining follow-up (6 percent in 2010). The volume of transplants performed by the program was not associated with the rate of reporting, suggesting that both large and small programs are able to continue to improve reporting of data.

Status 1 Liver Candidates Benefit from Full Regional Sharing
Embargo until Monday, May 20 – 2:39 p.m. PDT Authors: Erick B. Edwards, Ph.D.*, Ann M. Harper*, David C Mulligan, M.D., Kim M. Olthoff, M.D.

In 2010, liver allocation policy was changed to provide greater transplant access for candidates in the two highest medical urgency statuses (Status 1A and 1B). The policy directs that adult liver donors first be considered for any compatible Status 1A and 1B candidates within the region where the donation occurs before they are offered to less urgent candidates. The researchers studied comparable periods of time before and after policy implementation to assess the policy’s effects to date.

Since the policy has been in place, the rate of death on the waiting list has decreased for both adult and pediatric candidates in Status 1A and 1B, and the transplant rate within 90 days of listing has increased. The most benefit currently observed is for pediatric transplant candidates who have chronic liver disease.

Has Displaying the KDPI in DonorNet® Led to a Spike in Discard Rates for Lower Quality Kidneys?
Embargo until Monday, May 20 – 4:24 p.m. PEDT
Authors: Darren E. Stewart, M.S.*, Ciara J. Samana, M.P.H.*, Wida S. Cherikh, Ph.D.*, Richard Formica, M.D., John J. Friedewald, M.D.

DonorNet® is a secure, Internet-based program developed by UNOS for offers and placement of donor organs. In March 2012, all kidney offers in DonorNet® began displaying a statistical metric that estimates the likelihood of long-term function of a specific kidney offer. This metric is known as the Kidney Donor Profile Index (KDPI). It is intended to help transplant professionals better evaluate organ offers for individual candidates.

Anecdotal feedback suggested that displaying the metric discouraged placement of high KDPI kidneys (those with shorter estimated graft survival) and could increase the rate of kidney discards. The researchers calculated the KDPI score for all kidney donors recovered up to 12 months before implementation and up to 7 months afterward, and compared rates of kidney discards across both eras. They also evaluated the rate of offer refusals and cold ischemic times (amount of time spent preserving the organ in cold storage during transport) for transplanted kidneys, to assess whether displaying KDPI was resulting in longer placement times for high KDPI kidneys.

The discard rate for all kidneys, regardless of KDPI score, dropped slightly from pre- to post-implementation. The discard rate for high KDPI kidneys (those estimated to have shorter potential function) was very high both before and after implementation, but the rate was virtually unchanged over the two time periods. There were also no noticeable changes over time in patterns of cold ischemic time or the number of transplant hospitals refusing offers. The authors note that prospective efforts to develop more user-friendly “net benefit" calculations and incorporate KDPI into revised kidney allocation policy are expected to improve matching of donors with appropriate candidates, thus reducing offer refusals and organ discards.

Impact of Changing Patterns in Deceased Donor Cause of Death on Organs Transplanted per Donor
Embargo until Monday, May 20 – 5:30 p.m. PDT
Authors: Leah B. Edwards, Ph.D.*, John Rosendale*

As the distribution of causes of death for deceased donors has changed substantially in the last decade, the researchers examined possible effects on the number of organs transplanted per donor as well as geographic patterns.

While three causes of death -- cerebrovascular/stroke, head trauma and anoxia -- account for 98 percent of deceased donors, the proportion of deaths from those causes has changed dramatically from 2000 to 2012. The rate of anoxic deaths tripled, while proportions of cerebrovascular/stroke and head trauma declined somewhat. Deaths from anoxia are more likely to result in donation after circulatory death (DCD) than brain death; DCD is generally associated with a lower rate of organs transplanted per donor than brain death. The percentage of deaths from anoxia varied considerably among the 11 UNOS regions and 58 local donation service areas nationwide.

The researchers suggest that if these current trends persist for the next five years, there may be a slight decrease in the overall rate of organs transplanted per donor for brain death, while the rate of organs transplanted per DCD donor may not change.

The Organ Procurement and Transplantation Network (OPTN) Kidney Paired Donation Pilot Program (KPDPP): Review of Current Results
Embargo until Tuesday, May 21 – 2:15 p.m. PDT
Authors: Ruthanne Leishman, RN, M.P.H., CPTC*, Richard Formica, M.D., Kenneth A. Andreoni, M.D., John J. Friedewald, M.D., Elizabeth F. Sleeman, M.H.A.*, Catherine B. Monstello, CPHQ, RRT*, Darren E. Stewart, M.S.*, Tuomas Sandholm, Ph.D.

The Organ Procurement and Transplantation Network (OPTN) has operated a pilot program since October 2010 to facilitate kidney paired donation (KPD) transplants among participating members (128 transplant programs as of the time of the study). Through November 2012, programs had listed 610 transplant candidates and 673 donors (42 of whom were non-directed, meaning they did not have a specific recipient originally identified) for potential matches. Of these, 35 percent of candidates (212) had been identified in at least one match, and 27 candidates had received transplants. Of the matches that led to a transplant, the median time from match offer to transplant was 91 days.

Of match offers that were made, 93 percent (444 of 478) were declined. Of those, 53 percent were not an outright refusal, but rather the match could not have been accepted because other matches in the potential exchange had already been declined. Among outright refusals, the most common reason (36 percent) was a positive crossmatch or unacceptable antigen(s) that indicated the candidate’s immune system would reject the kidney.

The authors note several programmatic changes already introduced to the pilot program to increase the number of matches that proceed to a transplant. These include increasing the frequency of match runs, improving transplant programs’ ability to define acceptable matches by “pre-accepting” donors prior to match runs, and decreasing the maximum number of matches per chain. In the near future, “bridge” donors will also be included in the program to allow additional options for donor chains involving multiple matches.

An Early Look at Transplant Outcomes from the OPTN KPD Pilot Program: Comparing Cold Times and DGF Rates with Other Living and Deceased Donor Transplants
Embargo until Tuesday, May 21 – 2:27 p.m. PDT
Authors: Ruthanne Leishman, RN, M.P.H., CPTC*, Richard Formica, M.D., Kenneth A. Andreoni, M.D., John J. Friedewald, M.D., Elizabeth F. Sleeman, M.H.A.*, Catherine B. Monstello, CPHQ, RRT*, Darren E. Stewart, M.S.*, Tuomas Sandholm, Ph.D.

The authors examined data on transplants facilitated through the OPTN KPD pilot program between October 2010 and August 2012 in terms of cold ischemic time (the amount of time a donor kidney was preserved in a cold state outside the body between recovery and transplantation) and delayed graft function in the recipient (a need for dialysis within one week after the transplant). These results were compared with all other living donor and deceased donor transplants in the same time period.

Most transplants arranged through the pilot program involved kidneys recovered at one hospital and shipped to another, resulting in cold ischemic time (CIT) during transport. In these transplants, the median CIT was 8 hours. This was higher than the median CIT (4 hours) of all other living donor transplants involving different recovery and transplant centers. However, many of the transplants arranged by the OPTN program were transported beyond local and regional allocation areas, and the CIT for these transplants was nearly identical to other living donor transplants involving kidneys transported over similar distances.

None of the transplants arranged through the pilot program during the study period resulted in delayed graft function for the recipient. While this finding involves a limited population, the authors suggest that transporting kidneys 12 or more hours as part of the KPD program does not appear to significantly increase the risk of delayed graft function.

Tuning the OPTN’s Optimization Algorithm to Incentivize Centers to Enter Their “Easy-to-Match” Pairs
Embargo until Wednesday, May 22 – 9:30 a.m. PDT
Authors: Darren E. Stewart, M.S.*, Ruthanne Leishman, RN, M.P.H., CPTC*, Elizabeth F. Sleeman, M.H.A.*, Catherine B. Monstello, CPHQ, RRT*, Guy M. Lunsford*, Jude Maghirang, M.S.*, Tuomas Sandholm, Ph.D., Sommer E. Gentry, Ph.D., Richard Formica, M.D., John J. Friedewald, M.D., Kenneth A. Andreoni, M.D.

The Organ Procurement and Transplantation Network (OPTN) kidney paired donation pilot program uses a computer algorithm that awards point values for donor-recipient matching pairs based on a number of characteristics. As more potential donors and recipients are entered into the algorithm, the likelihood of finding more matches increases. However, it can be difficult to generate matches if many patients entered into the system have immune system sensitivity or many donors have blood types other than O.

The researchers used previous historical match runs from the program and reran the algorithm to see if more matches could have been generated if more points were awarded to donor-recipient combinations occurring within the same transplant hospital. Same-center matches are logistically easier and thus may provide hospitals centers greater incentive to enter additional donors and recipients into the matching system.

As point values were increased for “same-center” matching, the total number of matches decreased by nine percent. However, the number of same-center matches increased four-fold, from 4.5 percent to 19.2 percent of all matches. The vast majority of the increase came from same-center matches that could have been a part of a larger, non-directed donor chain involving multiple transplants. The authors suggest that increasing the likelihood of same-center matches may provide an incentive to enter more pairs that could be easier to match, thus providing more transplant opportunities for all potential recipients in the program.